diff --git a/zenoh/src/net/routing/hat/linkstate_peer/pubsub.rs b/zenoh/src/net/routing/hat/linkstate_peer/pubsub.rs
index 4b76e55387..8188e2c5e6 100644
--- a/zenoh/src/net/routing/hat/linkstate_peer/pubsub.rs
+++ b/zenoh/src/net/routing/hat/linkstate_peer/pubsub.rs
@@ -307,6 +307,14 @@ fn send_forget_sourced_subscription_to_net_childs(
 fn propagate_forget_simple_subscription(tables: &mut Tables, res: &Arc<Resource>) {
     for face in tables.faces.values_mut() {
         if let Some(id) = face_hat_mut!(face).local_subs.remove(res) {
+            // Still send WireExpr in UndeclareSubscriber to clients for pico
+            let ext_wire_expr = if face.whatami == WhatAmI::Client {
+                WireExprType {
+                    wire_expr: Resource::get_best_key(res, "", face.id),
+                }
+            } else {
+                WireExprType::null()
+            };
             face.primitives.send_declare(RoutingContext::with_expr(
                 Declare {
                     ext_qos: ext::QoSType::DECLARE,
@@ -314,7 +322,7 @@ fn propagate_forget_simple_subscription(tables: &mut Tables, res: &Arc<Resource>
                     ext_nodeid: ext::NodeIdType::DEFAULT,
                     body: DeclareBody::UndeclareSubscriber(UndeclareSubscriber {
                         id,
-                        ext_wire_expr: WireExprType::null(),
+                        ext_wire_expr,
                     }),
                 },
                 res.expr(),
@@ -412,6 +420,14 @@ pub(super) fn undeclare_client_subscription(
             let face = &mut client_subs[0];
             if !(face.whatami == WhatAmI::Client && res.expr().starts_with(PREFIX_LIVELINESS)) {
                 if let Some(id) = face_hat_mut!(face).local_subs.remove(res) {
+                    // Still send WireExpr in UndeclareSubscriber to clients for pico
+                    let ext_wire_expr = if face.whatami == WhatAmI::Client {
+                        WireExprType {
+                            wire_expr: Resource::get_best_key(res, "", face.id),
+                        }
+                    } else {
+                        WireExprType::null()
+                    };
                     face.primitives.send_declare(RoutingContext::with_expr(
                         Declare {
                             ext_qos: ext::QoSType::DECLARE,
@@ -419,7 +435,7 @@ pub(super) fn undeclare_client_subscription(
                             ext_nodeid: ext::NodeIdType::DEFAULT,
                             body: DeclareBody::UndeclareSubscriber(UndeclareSubscriber {
                                 id,
-                                ext_wire_expr: WireExprType::null(),
+                                ext_wire_expr,
                             }),
                         },
                         res.expr(),
diff --git a/zenoh/src/net/routing/hat/linkstate_peer/queries.rs b/zenoh/src/net/routing/hat/linkstate_peer/queries.rs
index d7f42120f0..6703769a4b 100644
--- a/zenoh/src/net/routing/hat/linkstate_peer/queries.rs
+++ b/zenoh/src/net/routing/hat/linkstate_peer/queries.rs
@@ -365,15 +365,20 @@ fn send_forget_sourced_queryable_to_net_childs(
 fn propagate_forget_simple_queryable(tables: &mut Tables, res: &mut Arc<Resource>) {
     for face in tables.faces.values_mut() {
         if let Some((id, _)) = face_hat_mut!(face).local_qabls.remove(res) {
+            // Still send WireExpr in UndeclareQueryable to clients for pico
+            let ext_wire_expr = if face.whatami == WhatAmI::Client {
+                WireExprType {
+                    wire_expr: Resource::get_best_key(res, "", face.id),
+                }
+            } else {
+                WireExprType::null()
+            };
             face.primitives.send_declare(RoutingContext::with_expr(
                 Declare {
                     ext_qos: ext::QoSType::DECLARE,
                     ext_tstamp: None,
                     ext_nodeid: ext::NodeIdType::DEFAULT,
-                    body: DeclareBody::UndeclareQueryable(UndeclareQueryable {
-                        id,
-                        ext_wire_expr: WireExprType::null(),
-                    }),
+                    body: DeclareBody::UndeclareQueryable(UndeclareQueryable { id, ext_wire_expr }),
                 },
                 res.expr(),
             ));
@@ -478,6 +483,14 @@ pub(super) fn undeclare_client_queryable(
         if client_qabls.len() == 1 && !peer_qabls {
             let face = &mut client_qabls[0];
             if let Some((id, _)) = face_hat_mut!(face).local_qabls.remove(res) {
+                // Still send WireExpr in UndeclareQueryable to clients for pico
+                let ext_wire_expr = if face.whatami == WhatAmI::Client {
+                    WireExprType {
+                        wire_expr: Resource::get_best_key(res, "", face.id),
+                    }
+                } else {
+                    WireExprType::null()
+                };
                 face.primitives.send_declare(RoutingContext::with_expr(
                     Declare {
                         ext_qos: ext::QoSType::DECLARE,
@@ -485,7 +498,7 @@ pub(super) fn undeclare_client_queryable(
                         ext_nodeid: ext::NodeIdType::DEFAULT,
                         body: DeclareBody::UndeclareQueryable(UndeclareQueryable {
                             id,
-                            ext_wire_expr: WireExprType::null(),
+                            ext_wire_expr,
                         }),
                     },
                     res.expr(),
diff --git a/zenoh/src/net/routing/hat/p2p_peer/pubsub.rs b/zenoh/src/net/routing/hat/p2p_peer/pubsub.rs
index 976466af12..22bd50eb3f 100644
--- a/zenoh/src/net/routing/hat/p2p_peer/pubsub.rs
+++ b/zenoh/src/net/routing/hat/p2p_peer/pubsub.rs
@@ -167,6 +167,14 @@ fn client_subs(res: &Arc<Resource>) -> Vec<Arc<FaceState>> {
 fn propagate_forget_simple_subscription(tables: &mut Tables, res: &Arc<Resource>) {
     for face in tables.faces.values_mut() {
         if let Some(id) = face_hat_mut!(face).local_subs.remove(res) {
+            // Still send WireExpr in UndeclareSubscriber to clients for pico
+            let ext_wire_expr = if face.whatami == WhatAmI::Client {
+                WireExprType {
+                    wire_expr: Resource::get_best_key(res, "", face.id),
+                }
+            } else {
+                WireExprType::null()
+            };
             face.primitives.send_declare(RoutingContext::with_expr(
                 Declare {
                     ext_qos: ext::QoSType::DECLARE,
@@ -174,7 +182,7 @@ fn propagate_forget_simple_subscription(tables: &mut Tables, res: &Arc<Resource>
                     ext_nodeid: ext::NodeIdType::DEFAULT,
                     body: DeclareBody::UndeclareSubscriber(UndeclareSubscriber {
                         id,
-                        ext_wire_expr: WireExprType::null(),
+                        ext_wire_expr,
                     }),
                 },
                 res.expr(),
@@ -201,6 +209,14 @@ pub(super) fn undeclare_client_subscription(
             let face = &mut client_subs[0];
             if !(face.whatami == WhatAmI::Client && res.expr().starts_with(PREFIX_LIVELINESS)) {
                 if let Some(id) = face_hat_mut!(face).local_subs.remove(res) {
+                    // Still send WireExpr in UndeclareSubscriber to clients for pico
+                    let ext_wire_expr = if face.whatami == WhatAmI::Client {
+                        WireExprType {
+                            wire_expr: Resource::get_best_key(res, "", face.id),
+                        }
+                    } else {
+                        WireExprType::null()
+                    };
                     face.primitives.send_declare(RoutingContext::with_expr(
                         Declare {
                             ext_qos: ext::QoSType::DECLARE,
@@ -208,7 +224,7 @@ pub(super) fn undeclare_client_subscription(
                             ext_nodeid: ext::NodeIdType::DEFAULT,
                             body: DeclareBody::UndeclareSubscriber(UndeclareSubscriber {
                                 id,
-                                ext_wire_expr: WireExprType::null(),
+                                ext_wire_expr,
                             }),
                         },
                         res.expr(),
diff --git a/zenoh/src/net/routing/hat/p2p_peer/queries.rs b/zenoh/src/net/routing/hat/p2p_peer/queries.rs
index d8d0a3fcc0..76c3675dca 100644
--- a/zenoh/src/net/routing/hat/p2p_peer/queries.rs
+++ b/zenoh/src/net/routing/hat/p2p_peer/queries.rs
@@ -164,15 +164,20 @@ fn client_qabls(res: &Arc<Resource>) -> Vec<Arc<FaceState>> {
 fn propagate_forget_simple_queryable(tables: &mut Tables, res: &mut Arc<Resource>) {
     for face in tables.faces.values_mut() {
         if let Some((id, _)) = face_hat_mut!(face).local_qabls.remove(res) {
+            // Still send WireExpr in UndeclareQueryable to clients for pico
+            let ext_wire_expr = if face.whatami == WhatAmI::Client {
+                WireExprType {
+                    wire_expr: Resource::get_best_key(res, "", face.id),
+                }
+            } else {
+                WireExprType::null()
+            };
             face.primitives.send_declare(RoutingContext::with_expr(
                 Declare {
                     ext_qos: ext::QoSType::DECLARE,
                     ext_tstamp: None,
                     ext_nodeid: ext::NodeIdType::DEFAULT,
-                    body: DeclareBody::UndeclareQueryable(UndeclareQueryable {
-                        id,
-                        ext_wire_expr: WireExprType::null(),
-                    }),
+                    body: DeclareBody::UndeclareQueryable(UndeclareQueryable { id, ext_wire_expr }),
                 },
                 res.expr(),
             ));
@@ -203,6 +208,14 @@ pub(super) fn undeclare_client_queryable(
         if client_qabls.len() == 1 {
             let face = &mut client_qabls[0];
             if let Some((id, _)) = face_hat_mut!(face).local_qabls.remove(res) {
+                // Still send WireExpr in UndeclareQueryable to clients for pico
+                let ext_wire_expr = if face.whatami == WhatAmI::Client {
+                    WireExprType {
+                        wire_expr: Resource::get_best_key(res, "", face.id),
+                    }
+                } else {
+                    WireExprType::null()
+                };
                 face.primitives.send_declare(RoutingContext::with_expr(
                     Declare {
                         ext_qos: ext::QoSType::DECLARE,
@@ -210,7 +223,7 @@ pub(super) fn undeclare_client_queryable(
                         ext_nodeid: ext::NodeIdType::DEFAULT,
                         body: DeclareBody::UndeclareQueryable(UndeclareQueryable {
                             id,
-                            ext_wire_expr: WireExprType::null(),
+                            ext_wire_expr,
                         }),
                     },
                     res.expr(),
diff --git a/zenoh/src/net/routing/hat/router/pubsub.rs b/zenoh/src/net/routing/hat/router/pubsub.rs
index 2e7b22894d..e349fc7df9 100644
--- a/zenoh/src/net/routing/hat/router/pubsub.rs
+++ b/zenoh/src/net/routing/hat/router/pubsub.rs
@@ -404,6 +404,14 @@ fn send_forget_sourced_subscription_to_net_childs(
 fn propagate_forget_simple_subscription(tables: &mut Tables, res: &Arc<Resource>) {
     for face in tables.faces.values_mut() {
         if let Some(id) = face_hat_mut!(face).local_subs.remove(res) {
+            // Still send WireExpr in UndeclareSubscriber to clients for pico
+            let ext_wire_expr = if face.whatami == WhatAmI::Client {
+                WireExprType {
+                    wire_expr: Resource::get_best_key(res, "", face.id),
+                }
+            } else {
+                WireExprType::null()
+            };
             face.primitives.send_declare(RoutingContext::with_expr(
                 Declare {
                     ext_qos: ext::QoSType::DECLARE,
@@ -411,7 +419,7 @@ fn propagate_forget_simple_subscription(tables: &mut Tables, res: &Arc<Resource>
                     ext_nodeid: ext::NodeIdType::DEFAULT,
                     body: DeclareBody::UndeclareSubscriber(UndeclareSubscriber {
                         id,
-                        ext_wire_expr: WireExprType::null(),
+                        ext_wire_expr,
                     }),
                 },
                 res.expr(),
@@ -429,6 +437,14 @@ fn propagate_forget_simple_subscription(tables: &mut Tables, res: &Arc<Resource>
                     .contains(&tables.zid)
             }) {
                 if let Some(id) = face_hat_mut!(face).local_subs.remove(&res) {
+                    // Still send WireExpr in UndeclareSubscriber to clients for pico
+                    let ext_wire_expr = if face.whatami == WhatAmI::Client {
+                        WireExprType {
+                            wire_expr: Resource::get_best_key(&res, "", face.id),
+                        }
+                    } else {
+                        WireExprType::null()
+                    };
                     face.primitives.send_declare(RoutingContext::with_expr(
                         Declare {
                             ext_qos: ext::QoSType::DECLARE,
@@ -436,7 +452,7 @@ fn propagate_forget_simple_subscription(tables: &mut Tables, res: &Arc<Resource>
                             ext_nodeid: ext::NodeIdType::DEFAULT,
                             body: DeclareBody::UndeclareSubscriber(UndeclareSubscriber {
                                 id,
-                                ext_wire_expr: WireExprType::null(),
+                                ext_wire_expr,
                             }),
                         },
                         res.expr(),
@@ -469,6 +485,14 @@ fn propagate_forget_simple_subscription_to_peers(tables: &mut Tables, res: &Arc<
                 })
             {
                 if let Some(id) = face_hat_mut!(&mut face).local_subs.remove(res) {
+                    // Still send WireExpr in UndeclareSubscriber to clients for pico
+                    let ext_wire_expr = if face.whatami == WhatAmI::Client {
+                        WireExprType {
+                            wire_expr: Resource::get_best_key(res, "", face.id),
+                        }
+                    } else {
+                        WireExprType::null()
+                    };
                     face.primitives.send_declare(RoutingContext::with_expr(
                         Declare {
                             ext_qos: ext::QoSType::DECLARE,
@@ -476,7 +500,7 @@ fn propagate_forget_simple_subscription_to_peers(tables: &mut Tables, res: &Arc<
                             ext_nodeid: ext::NodeIdType::DEFAULT,
                             body: DeclareBody::UndeclareSubscriber(UndeclareSubscriber {
                                 id,
-                                ext_wire_expr: WireExprType::null(),
+                                ext_wire_expr,
                             }),
                         },
                         res.expr(),
@@ -620,6 +644,14 @@ pub(super) fn undeclare_client_subscription(
             let face = &mut client_subs[0];
             if !(face.whatami == WhatAmI::Client && res.expr().starts_with(PREFIX_LIVELINESS)) {
                 if let Some(id) = face_hat_mut!(face).local_subs.remove(res) {
+                    // Still send WireExpr in UndeclareSubscriber to clients for pico
+                    let ext_wire_expr = if face.whatami == WhatAmI::Client {
+                        WireExprType {
+                            wire_expr: Resource::get_best_key(res, "", face.id),
+                        }
+                    } else {
+                        WireExprType::null()
+                    };
                     face.primitives.send_declare(RoutingContext::with_expr(
                         Declare {
                             ext_qos: ext::QoSType::DECLARE,
@@ -627,7 +659,7 @@ pub(super) fn undeclare_client_subscription(
                             ext_nodeid: ext::NodeIdType::DEFAULT,
                             body: DeclareBody::UndeclareSubscriber(UndeclareSubscriber {
                                 id,
-                                ext_wire_expr: WireExprType::null(),
+                                ext_wire_expr,
                             }),
                         },
                         res.expr(),
@@ -810,16 +842,21 @@ pub(super) fn pubsub_linkstate_change(tables: &mut Tables, zid: &ZenohId, links:
                                         })
                                     };
                                 if forget {
+                                    // Still send WireExpr in UndeclareSubscriber to clients for pico
+                                    let ext_wire_expr = if dst_face.whatami == WhatAmI::Client {
+                                        WireExprType {
+                                            wire_expr: Resource::get_best_key(res, "", dst_face.id),
+                                        }
+                                    } else {
+                                        WireExprType::null()
+                                    };
                                     dst_face.primitives.send_declare(RoutingContext::with_expr(
                                         Declare {
                                             ext_qos: ext::QoSType::DECLARE,
                                             ext_tstamp: None,
                                             ext_nodeid: ext::NodeIdType::DEFAULT,
                                             body: DeclareBody::UndeclareSubscriber(
-                                                UndeclareSubscriber {
-                                                    id,
-                                                    ext_wire_expr: WireExprType::null(),
-                                                },
+                                                UndeclareSubscriber { id, ext_wire_expr },
                                             ),
                                         },
                                         res.expr(),
diff --git a/zenoh/src/net/routing/hat/router/queries.rs b/zenoh/src/net/routing/hat/router/queries.rs
index ddf8ef2226..8f87dc055f 100644
--- a/zenoh/src/net/routing/hat/router/queries.rs
+++ b/zenoh/src/net/routing/hat/router/queries.rs
@@ -507,15 +507,20 @@ fn send_forget_sourced_queryable_to_net_childs(
 fn propagate_forget_simple_queryable(tables: &mut Tables, res: &mut Arc<Resource>) {
     for face in tables.faces.values_mut() {
         if let Some((id, _)) = face_hat_mut!(face).local_qabls.remove(res) {
+            // Still send WireExpr in UndeclareQueryable to clients for pico
+            let ext_wire_expr = if face.whatami == WhatAmI::Client {
+                WireExprType {
+                    wire_expr: Resource::get_best_key(res, "", face.id),
+                }
+            } else {
+                WireExprType::null()
+            };
             face.primitives.send_declare(RoutingContext::with_expr(
                 Declare {
                     ext_qos: ext::QoSType::DECLARE,
                     ext_tstamp: None,
                     ext_nodeid: ext::NodeIdType::DEFAULT,
-                    body: DeclareBody::UndeclareQueryable(UndeclareQueryable {
-                        id,
-                        ext_wire_expr: WireExprType::null(),
-                    }),
+                    body: DeclareBody::UndeclareQueryable(UndeclareQueryable { id, ext_wire_expr }),
                 },
                 res.expr(),
             ));
@@ -533,6 +538,14 @@ fn propagate_forget_simple_queryable(tables: &mut Tables, res: &mut Arc<Resource
                     .any(|zid| zid == &tables.zid)
             }) {
                 if let Some((id, _)) = face_hat_mut!(face).local_qabls.remove(&res) {
+                    // Still send WireExpr in UndeclareQueryable to clients for pico
+                    let ext_wire_expr = if face.whatami == WhatAmI::Client {
+                        WireExprType {
+                            wire_expr: Resource::get_best_key(&res, "", face.id),
+                        }
+                    } else {
+                        WireExprType::null()
+                    };
                     face.primitives.send_declare(RoutingContext::with_expr(
                         Declare {
                             ext_qos: ext::QoSType::DECLARE,
@@ -540,7 +553,7 @@ fn propagate_forget_simple_queryable(tables: &mut Tables, res: &mut Arc<Resource
                             ext_nodeid: ext::NodeIdType::DEFAULT,
                             body: DeclareBody::UndeclareQueryable(UndeclareQueryable {
                                 id,
-                                ext_wire_expr: WireExprType::null(),
+                                ext_wire_expr,
                             }),
                         },
                         res.expr(),
@@ -573,6 +586,14 @@ fn propagate_forget_simple_queryable_to_peers(tables: &mut Tables, res: &mut Arc
                 })
             {
                 if let Some((id, _)) = face_hat_mut!(&mut face).local_qabls.remove(res) {
+                    // Still send WireExpr in UndeclareQueryable to clients for pico
+                    let ext_wire_expr = if face.whatami == WhatAmI::Client {
+                        WireExprType {
+                            wire_expr: Resource::get_best_key(res, "", face.id),
+                        }
+                    } else {
+                        WireExprType::null()
+                    };
                     face.primitives.send_declare(RoutingContext::with_expr(
                         Declare {
                             ext_qos: ext::QoSType::DECLARE,
@@ -580,7 +601,7 @@ fn propagate_forget_simple_queryable_to_peers(tables: &mut Tables, res: &mut Arc
                             ext_nodeid: ext::NodeIdType::DEFAULT,
                             body: DeclareBody::UndeclareQueryable(UndeclareQueryable {
                                 id,
-                                ext_wire_expr: WireExprType::null(),
+                                ext_wire_expr,
                             }),
                         },
                         res.expr(),
@@ -735,6 +756,14 @@ pub(super) fn undeclare_client_queryable(
         if client_qabls.len() == 1 && !router_qabls && !peer_qabls {
             let face = &mut client_qabls[0];
             if let Some((id, _)) = face_hat_mut!(face).local_qabls.remove(res) {
+                // Still send WireExpr in UndeclareQueryable to clients for pico
+                let ext_wire_expr = if face.whatami == WhatAmI::Client {
+                    WireExprType {
+                        wire_expr: Resource::get_best_key(res, "", face.id),
+                    }
+                } else {
+                    WireExprType::null()
+                };
                 face.primitives.send_declare(RoutingContext::with_expr(
                     Declare {
                         ext_qos: ext::QoSType::DECLARE,
@@ -742,7 +771,7 @@ pub(super) fn undeclare_client_queryable(
                         ext_nodeid: ext::NodeIdType::DEFAULT,
                         body: DeclareBody::UndeclareQueryable(UndeclareQueryable {
                             id,
-                            ext_wire_expr: WireExprType::null(),
+                            ext_wire_expr,
                         }),
                     },
                     res.expr(),
@@ -881,16 +910,21 @@ pub(super) fn queries_linkstate_change(tables: &mut Tables, zid: &ZenohId, links
                                         })
                                     };
                                 if forget {
+                                    // Still send WireExpr in UndeclareQueryable to clients for pico
+                                    let ext_wire_expr = if dst_face.whatami == WhatAmI::Client {
+                                        WireExprType {
+                                            wire_expr: Resource::get_best_key(res, "", dst_face.id),
+                                        }
+                                    } else {
+                                        WireExprType::null()
+                                    };
                                     dst_face.primitives.send_declare(RoutingContext::with_expr(
                                         Declare {
                                             ext_qos: ext::QoSType::DECLARE,
                                             ext_tstamp: None,
                                             ext_nodeid: ext::NodeIdType::DEFAULT,
                                             body: DeclareBody::UndeclareQueryable(
-                                                UndeclareQueryable {
-                                                    id,
-                                                    ext_wire_expr: WireExprType::null(),
-                                                },
+                                                UndeclareQueryable { id, ext_wire_expr },
                                             ),
                                         },
                                         res.expr(),