>>395471926
Thank you! I already know how to actually set things up (have uploaded an avatar before with custom expressions), I just don't want to redo the process of doing it every single time I want to upload it with a new outfit (not toggle because I have too many outfit ideas)+(pure reasons only). 
I was thinking of just putting the base in unity, adding all the menus/expressions/etc., saving it as "base", then whenever I wanted a new outfit I'd create/edit it (aka transfer weights) in blender and then add it to a copy of "base.unitypackage". 
Don't know if that'd actually work due to the bones though. Maybe they'll merge together in unity. 
If there are holes in my plan and you know a better way please tell me.