Using joints brake the relationship parent-child

Hi guys,

I am sure that I am missing some very basic things here, but I can’t figure it out what.

I have 2 object in my scene, each with a parented box collider. I would like to join these 2 objects just when the two boxes collide with each other (like 2 parachutists that at some point join hands) . I’ve tried different joint types but apparently all of them are destroying my geometry aka the colliders form a regular well working connection but then the objects get separated from them, and move on their own. I’ve tried to form the joint from collider to collider and from collider to object, but no good results!
Any idea of why this is happening? Any suggestion for a different approach?

Thank you in advance for any help!

I think I narrowed down the problem… when I add the hinge joint Unity always add a rigidbody, and having 2 parented rigid bodies moving around… is not a good idea!
I solved the issue using kinematic rigid body triggers and placing the joint on the root.