BTW, that reminds me that at 11, I decided I wanted to be christened and begged my parents to let me. My mum was a bit taken aback, but instead of saying no, said that we would look into it at the end of the school year.
The reason I wanted it is because all my friends used to go to church group on Sunday afternoon and had a great time. The village priest was very flexible and let me join, even allowed me to participate in all the ceremonies. At that time, I really did feel no different to my friends and therefore Catholic so it made sense to go ahead and be christened.
As it happened, we moved at the end of that year, I made new friends, who didn't go to church, and funnily enough, I lost all interest in becoming a Catholic and being christened.
7 is definitely way too young to have valid reason for wanting to change their names. If the issue is having a different name than mum and siblings, then it can be made to be a positive things. When OH and kids travel together, we laugh as we have three different names and two different nationalities on our passport (kids have double nationality, but one travels with one passport, the other their British one). We make fun of it and the kids don't mind at all, on the opposite, we think it is funny to see official faces when we go through passport control.