diff --git a/tests/ConditionSqlTest.php b/tests/ConditionSqlTest.php
index 3e9e97d87..d3e3f00d3 100644
--- a/tests/ConditionSqlTest.php
+++ b/tests/ConditionSqlTest.php
@@ -286,6 +286,63 @@ public function testExpressionJoin(): void
         static::assertSame('+123 smiths', $mm2->get('contact_phone'));
     }
 
+    public function testExpressionJoinForeignCustomIdField(): void
+    {
+        $this->setDb([
+            'user' => [
+                1 => ['id' => 1, 'name' => 'John', 'surname' => 'Smith', 'gender' => 'M', 'contact_id' => 1],
+                2 => ['id' => 2, 'name' => 'Sue', 'surname' => 'Sue', 'gender' => 'F', 'contact_id' => 2],
+                3 => ['id' => 3, 'name' => 'Peter', 'surname' => 'Smith', 'gender' => 'M', 'contact_id' => 1],
+            ],
+            'contact' => [
+                1 => ['custom_id' => 1, 'contact_id' => 1, 'contact_phone' => '+123 smiths'],
+                2 => ['custom_id' => 2, 'contact_id' => 2, 'contact_phone' => '+321 sues'],
+            ],
+        ]);
+
+        $m = new Model($this->db, ['table' => 'user']);
+        $m->addField('name');
+        $m->addField('gender');
+        $m->addField('surname');
+
+        $m->join('contact', [
+            'masterField' => 'contact_id',
+            'foreignField' => 'contact_id',
+            'foreignModelIdField' => 'custom_id'
+        ])->addField('contact_phone');
+
+        $mm2 = $m->load(1);
+        static::assertSame('John', $mm2->get('name'));
+        static::assertSame('+123 smiths', $mm2->get('contact_phone'));
+        $mm2 = $m->load(2);
+        static::assertSame('Sue', $mm2->get('name'));
+        static::assertSame('+321 sues', $mm2->get('contact_phone'));
+        $mm2 = $m->load(3);
+        static::assertSame('Peter', $mm2->get('name'));
+        static::assertSame('+123 smiths', $mm2->get('contact_phone'));
+
+        $mm = clone $m;
+        $mm->addCondition($mm->expr('[name] = [surname]'));
+        $mm2 = $mm->tryLoad(1);
+        static::assertNull($mm2);
+        $mm2 = $mm->load(2);
+        static::assertSame('Sue', $mm2->get('name'));
+        static::assertSame('+321 sues', $mm2->get('contact_phone'));
+        $mm2 = $mm->tryLoad(3);
+        static::assertNull($mm2);
+
+        $mm = clone $m;
+        $mm->addCondition($mm->expr('\'+123 smiths\' = [contact_phone]'));
+        $mm2 = $mm->load(1);
+        static::assertSame('John', $mm2->get('name'));
+        static::assertSame('+123 smiths', $mm2->get('contact_phone'));
+        $mm2 = $mm->tryLoad(2);
+        static::assertNull($mm2);
+        $mm2 = $mm->load(3);
+        static::assertSame('Peter', $mm2->get('name'));
+        static::assertSame('+123 smiths', $mm2->get('contact_phone'));
+    }
+
     public function testArrayCondition(): void
     {
         $this->setDb([
diff --git a/tests/JoinSqlTest.php b/tests/JoinSqlTest.php
index 3e462f956..b4dda714b 100644
--- a/tests/JoinSqlTest.php
+++ b/tests/JoinSqlTest.php
@@ -6,6 +6,7 @@
 
 use Atk4\Data\Exception;
 use Atk4\Data\Model;
+use Atk4\Data\Persistence;
 use Atk4\Data\Schema\TestCase;
 use Doctrine\DBAL\Platforms\MySQLPlatform;
 
@@ -762,4 +763,230 @@ public function testJoinActualFieldNamesAndPrefix(): void
             ],
         ], $this->getDb());
     }
+
+    public function testJoinSavingForeignCustomIdFieldRaiseException(): void
+    {
+        $this->expectException(\Atk4\Data\Persistence\Sql\ExecuteException::class);
+
+        $master_model = new \Atk4\Data\Model($this->db, [
+            'table' => 'user_join',
+        ]);
+        $master_model->addField('name');
+        $master_model->addField('test_id');
+
+        $joined_model = new \Atk4\Data\Model($this->db, [
+            'table' => 'contact_join',
+            'idField' => 'not_named_id',
+        ]);
+        $joined_model->addField('contact_id');
+        $joined_model->addField('contact_phone');
+
+        $this->createMigrator($master_model)->create();
+        $this->createMigrator($joined_model)->create();
+
+        $master_model->import([
+            [
+                'id' => 1,
+                'name' => 'John',
+                'test_id' => 21,
+            ],
+        ]);
+
+        $joined_model->import([
+            [
+                'not_named_id' => 1,
+                'contact_id' => 21,
+                'contact_phone' => '+123',
+            ],
+        ]);
+
+        $user = new Model($this->db, ['table' => 'user_join']);
+        $user->addField('name');
+        $j = $user->join('contact_join', [
+            'foreignTable'        => 'contact_join',
+            'masterField'         => 'test_id',
+            'foreignField'        => 'contact_id',
+            //'foreignModelIdField' => 'not_named_id',
+        ]);
+        $this->createMigrator()->createForeignKey($j);
+        $j->addField('contact_phone');
+
+        $user = $user->load(1);
+
+        $user->set('name', 'John');
+        $user->set('contact_phone', '+321');
+
+        $user->save();
+    }
+
+    public function testJoinSavingForeignCustomIdField(): void
+    {
+        $master_model = new \Atk4\Data\Model($this->db, [
+            'table' => 'user_join',
+        ]);
+        $master_model->addField('name');
+        $master_model->addField('test_id');
+
+        $joined_model = new \Atk4\Data\Model($this->db, [
+            'table' => 'contact_join',
+            'idField' => 'not_named_id',
+        ]);
+        $joined_model->addField('contact_id');
+        $joined_model->addField('contact_phone');
+
+        $this->createMigrator($master_model)->create();
+        $this->createMigrator($joined_model)->create();
+
+        $master_model->import([
+            [
+                'id' => 1,
+                'name' => 'John',
+                'test_id' => 21,
+            ],
+        ]);
+
+        $joined_model->import([
+            [
+                'not_named_id' => 1,
+                'contact_id' => 21,
+                'contact_phone' => '+123',
+            ],
+        ]);
+
+        $user = new Model($this->db, ['table' => 'user_join']);
+        $user->addField('name');
+        $j = $user->join('contact_join', [
+            'masterField'         => 'test_id',
+            'foreignField'        => 'contact_id',
+            'foreignModelIdField' => 'not_named_id',
+        ]);
+        $this->createMigrator()->createForeignKey($j);
+        $j->addField('contact_phone');
+
+        $user = $user->load(1);
+
+        $user->set('name', 'John');
+        $user->set('contact_phone', '+321');
+
+        $user->save();
+
+        static::assertSame([
+            'user_join' => [
+                1 => ['id' => 1, 'name' => 'John', 'test_id' => '21'],
+            ],
+            'contact_join' => [
+                1 => ['not_named_id' => 1, 'contact_id' => '21', 'contact_phone' => '+321'],
+            ],
+        ], [
+            'user_join' => [
+                1 => $master_model->load(1)->get(),
+            ],
+            'contact_join' => [
+                1 => $joined_model->load(1)->get(),
+            ],
+        ]);
+    }
+
+    public function testJoinDeleteForeignCustomIdField(): void
+    {
+        $master_model = new \Atk4\Data\Model($this->db, [
+            'table' => 'user_join',
+        ]);
+        $master_model->addField('name');
+        $master_model->addField('test_id');
+
+        $this->createMigrator($master_model)->create();
+
+        $master_model->import([
+            [
+                'id' => 1,
+                'name' => 'John',
+                'test_id' => 21,
+            ],
+        ]);
+
+        $joined_model = new \Atk4\Data\Model($this->db, [
+            'table' => 'contact_join',
+            'idField' => 'not_named_id',
+        ]);
+        $joined_model->addField('contact_id');
+        $joined_model->addField('contact_phone');
+
+        $this->createMigrator($joined_model)->create();
+
+        $joined_model->import([
+            [
+                'not_named_id' => 1,
+                'contact_id' => 21,
+                'contact_phone' => '+123',
+            ],
+        ]);
+
+        $user = new Model($this->db, ['table' => 'user_join']);
+        $user->addField('name');
+        $j = $user->join('contact_join', [
+            'masterField'         => 'test_id',
+            'foreignField'        => 'contact_id',
+            'foreignModelIdField' => 'not_named_id',
+        ]);
+        $this->createMigrator()->createForeignKey($j);
+        $j->addField('contact_phone');
+
+        $user->delete(1);
+
+        static::assertSame(null, $master_model->tryLoad(1));
+        static::assertSame(null, $joined_model->tryLoad(1));
+    }
+
+    public function testJoinDeleteForeignCustomIdFieldReverse(): void
+    {
+        $master_model = new \Atk4\Data\Model($this->db, [
+            'table' => 'user_join',
+        ]);
+        $master_model->addField('name');
+        $master_model->addField('test_id');
+
+        $this->createMigrator($master_model)->create();
+
+        $master_model->import([
+            [
+                'id' => 1,
+                'name' => 'John',
+                'test_id' => 21,
+            ],
+        ]);
+
+        $joined_model = new \Atk4\Data\Model($this->db, [
+            'table' => 'contact_join',
+            'idField' => 'not_named_id',
+        ]);
+        $joined_model->addField('contact_id');
+        $joined_model->addField('contact_phone');
+
+        $this->createMigrator($joined_model)->create();
+
+        $joined_model->import([
+            [
+                'not_named_id' => 1,
+                'contact_id' => 21,
+                'contact_phone' => '+123',
+            ],
+        ]);
+
+        $user = new Model($this->db, ['table' => 'user_join']);
+        $user->addField('name');
+        $j = $user->join('contact_join', [
+            'masterField'         => 'test_id',
+            'foreignField'        => 'contact_id',
+            'foreignModelIdField' => 'not_named_id',
+            'reverse' => true,
+        ]);
+        $this->createMigrator()->createForeignKey($j);
+        $j->addField('contact_phone');
+
+        $user->delete(1);
+
+        static::assertSame(null, $master_model->tryLoad(1));
+        static::assertSame(null, $joined_model->tryLoad(1));
+    }
 }