Hello
I have a scene with a lot of armatures and I want them to be only one rigged big model by merging them with Ctrl+J , but it doesn’t keep the action from one of the armatures + it break the armatures and deforms it,
so I looked for a solution on google
here some solutions I found
-Different names for all bones 
Done
-Applying transforms on objects Done
-Applying transforms on armatures 
Error —> it breaks the armature and the animations
it seems that this problem has no solution 
please I need help this is a big project for me
the blend file