do you have any idea how to fix this?
EDIT: I'm not sure that my post is a duplicate of the other one, I managed to join the armatures by having proper names, then merging the two objects (Crtl+J), Applying transforms, putting two armature modifiers on the object instead of one, and finally, merging the armatures ... The weights are ok, but there is two problems: the action of the second armature is deleted and the armature is like slightly deformed ,
to fix the action missing I've copied the action before the merge and paste it in the graph editor after the merge, at first the animation kinda looks like it works, but then it goes all over the place ...
EDIT2: so it's not possible to merge armature with the actions attached to it, plus merging armatures with scales not applied properly (and I can't apply scales on it because it breaks the animations) deforms everything. It seems that there is no solution apart from do all the animations again (1600 frames), something that a can't afford to do, in other words, I'm f****d, its a project I've been working on for weeks and there is no solution.
I'm depressed right now 😢