your seven year old is acting like a seven year old.
experimenting with the world, emulating others, testing authority, along with many other things, is all part of growing up.
if you take the scissors and hair cutting away and substitute: touching the hot dinner plate after being warned or putting on moms lip stick. you would have the same experimenting, learning by doing, that children do. its just that sometimes children experimenting with the world has tougher consequences then others. its hard to watch children learning sometimes, that's all.
bad behavior in children is easy to spot. you'll know if there is any malice there.
as for you relatives? well, we all have them, we just never get to pick them.
all the best to you and your daughter, the budding beautician.