Collision problem with dynamically created compound objects

Hello all. (I'm a french guy so I prefer apologize for my language)

Here my current problem.
I have two GameObject :
GameObject A with a Rigidbody, a CapsuleCollider and a CustomJoint (with some motion and angular constraints but no Connected Body).
GameObject B with only a CapsuleCollider.

If I do parenting object B to object A before launching the engine, I obtain a fully correct compound object with a collider formed by the two capsules.
But if I try to do parenting at runtime (with the Hierarchy panel or by scripting) the result compound object has a correct physical behavior (A and B moves correctly together) but the object B doesn't collide anymore with the ground (Terrain).

Do you ever meet this type of problem and have you an idea to fix it ?

Thanks in advance for your help.

 

After several tests, I found a bit more informations about my problem.

If I do parenting B to A out of runtime
objectB.collider.attachedRigidbody correspond to the rigidbody of the A object. It's ok.

But if I do parenting B to A at runtime
objectB.collider.attachedRigidbody is NULL. This is abnormal.

Someone can explain to me why, please ?

 

The rigidbody doesn't recognise child colliders added to an existing object. If you destroy the existing rigidbody component and then add a new one after the new object is parented, it will incorporate both colliders correctly:-

Code (csharp):

1. B.parent = transform;
2. DestroyImmediate(rigidbody);
3. gameObject.AddComponent(Rigidbody);

 

Thank you for your answer and your helpful tip.
I found a mean to create the rigidbody after all the colliders and the problem is now fixed.