Physics simulation. I need to join two actors

hi, I need to join two objects, but to merge them, because I also need them to be affected by external forces, to break them if they are too heavy, to bend by the weight. I was using Physics Constraints but it does not give me the results I want, if I apply a lot of force they bend like rubber, they are very flexible, I need them to be rigid, like a real union of metal, I need them to bend very little.

Any suggestions? Thank you