As far as changing the diet over, just go ahead and do it. I've done it with ten gliders through the years, and have never, ever had a negative experience. With the crummy diet they've been on, they will SOOOOOO love eating some real food!
As a cautionary note, though, I would be VERY reluctant to put Boo in with two males, neutered or not, because it is very likely that they will fight over her. Two girls and a boy, no problem. Two boys not related to the girl and a girl, generally a big problem. I do have one colony with two neutered boys and a girl, but one of the neutered boys (Miles) was neutered at 12 weeks, and he's never shown any sexual behaviors towards his mom. Thus, this little family seems to be just fine. I think this is more the exception than the rule, though.
Generally speaking, you want the number of girls to be at least equal to (or greater than) the number of boys in a colony.