so you can't just export and weld or weld inside blender?
it sounds like you're saying you have to do it manually... yes, i wouldn't be able to do that I don't think, cause I don't model... is there a tool that does that automatically somehow

I've tried constrained groups, but it doesn't hold it together, not sure how choreographed works... but I assume if constrained doesn't work choreographed wouldn't either or am I wrong?