Don't Make Me Release The Flying Monkeys

I think it best to make sure your brother is okay with whatever you do. For example, if he had said "I don't want my daughter wearing high heels" it might not necessarily be because he couldn't afford them, but thought she was too young to wear them, meaning "please don't buy them for her because I won't let her wear them anyway." He may have said the "can't afford it" as one of the reasons, but he may have other reasons too and think it is important to respect someone's rules for their own child. Better to not make an awkward situation with your brother and check first before doing anything. Nothing more frustrating to a parent than a grandparent or other relative who makes them look like the bad guy.