If a realitive lives same apartment complex can I use there address

They're ok with me using there addres but I already did refund with a store if I wanted to use same store but use my family member apartment # instead of mine would it be ok? We both live in same complex

also

I recently used refund for a store now I want to do another store but it's not the same store... Can i still use same paypal account or I have to use another one?