diff --git a/internal/controller/graph/dag.go b/internal/controller/graph/dag.go
index e14391d4d55..f686ced7621 100644
--- a/internal/controller/graph/dag.go
+++ b/internal/controller/graph/dag.go
@@ -23,6 +23,8 @@ import (
 	"errors"
 	"fmt"
 	"sort"
+
+	"golang.org/x/exp/maps"
 )
 
 type DAG struct {
@@ -260,10 +262,12 @@ func (d *DAG) Root() Vertex {
 
 func (d *DAG) Merge(subDag *DAG) {
 	for v := range subDag.vertices {
-		if len(d.inAdj(v)) == 0 {
-			d.AddConnectRoot(v)
+		if len(subDag.inAdj(v)) == 0 {
+			d.Connect(d.Root(), v)
 		}
 	}
+	maps.Copy(d.vertices, subDag.vertices)
+	maps.Copy(d.edges, subDag.edges)
 }
 
 // String returns a string representation of the DAG in topology order
diff --git a/internal/controller/graph/dag_test.go b/internal/controller/graph/dag_test.go
index 1e019929fc1..ac782bcce3a 100644
--- a/internal/controller/graph/dag_test.go
+++ b/internal/controller/graph/dag_test.go
@@ -306,20 +306,37 @@ func TestEquals(t *testing.T) {
 func TestMerge(t *testing.T) {
 	dag1 := NewDAG()
 	dag2 := NewDAG()
-	v1, v2, v3 := 1, 2, 3
+	v1, v2, v3, v4, v5, v6 := 1, 2, 3, 4, 5, 6
 	dag1.AddVertex(v1)
 	dag1.AddVertex(v2)
 	dag1.Connect(v1, v2)
 	dag2.AddVertex(v2)
 	dag2.AddVertex(v3)
+	dag2.AddVertex(v4)
+	dag2.AddVertex(v5)
+	dag2.AddVertex(v6)
 	dag2.Connect(v2, v3)
+	dag2.Connect(v2, v4)
+	dag2.Connect(v3, v5)
+	dag2.Connect(v4, v5)
+	dag2.Connect(v6, v4)
+	dag2.Connect(v6, v5)
 
 	dagExpected := NewDAG()
 	dagExpected.AddVertex(v1)
 	dagExpected.AddVertex(v2)
 	dagExpected.AddVertex(v3)
+	dagExpected.AddVertex(v4)
+	dagExpected.AddVertex(v5)
+	dagExpected.AddVertex(v6)
 	dagExpected.Connect(v1, v2)
-	dagExpected.Connect(v1, v3)
+	dagExpected.Connect(v1, v6)
+	dagExpected.Connect(v2, v3)
+	dagExpected.Connect(v2, v4)
+	dagExpected.Connect(v3, v5)
+	dagExpected.Connect(v4, v5)
+	dagExpected.Connect(v6, v4)
+	dagExpected.Connect(v6, v5)
 
 	dag1.Merge(dag2)
 	if !dag1.Equals(dagExpected, less) {