Adding group element to linked object

Hello, I linked an mesh with armature from a library and there was grouped together in the library file, I made a proxy to the armature and started some animation, but I forgot to add an object to the group before that. Then I added the object to the group in the library file but now if I link the object it won’t be together with the mesh.

Is there a way to do that or must I delete and link again ?