lily lily:
You either remove the spare limbs or you leave them. There aren't really any other options.
I think the only real option is to perform the surgery to allow her to lead as "normal" a life as possible. Abilities aside, imagine the teasing and strange looks she'll have to endure, as well as the difficulty in such simple things as buying clothes.
The matter will be moot, hopefully, with the successful completion of the surgery and recovery process.