Two similar characters workflow

I’m making a character and will create his “brother” which is a very similar guy, but with bigger arms and legs and also he’s shorter and has a different texture (with the same UV). Other than that I’ve prepared facial rigs which is suitable for both chatacters. The armature is slightly different due to the length but it has all the same bones.

How can I best set this up, in case i realize i need another facial expression (shape key) or pose in both characters?

Or do I need to edit both manually once I duplicate them?