Yes, them.
I asked because in Aigis you can evolve girls before they reach maximum level, but to maximize their potential you are supposed to max their level first.
I was wondering if something like that can be present Flower Girl too: while you can only evolve at max level, you can use boosts before evolution. So, I am wondering if there was something like this here too: i.e. you can/have to use boost again after evolution, but % of old boosts remain, so if you boost the girl before evolution as well, she will be stronger in the end.