I would just leave them alone, they probably won't separate the kids, they'll probably just feed them all, one big happy family. The only thing I would watch is to be sure the girl is getting plenty, if only one mom is feeding her plus the 3 free loaders.
Last year I had a doe help raise another does kid (only one, she didn't feed the kid's twin). But this year I had 3 go in 3 days and there has been alot of sharing. First mom only had one surviving kid that needed special care so was pulled, second mom had twins and for that first day these two moms just shared. Third mom went w/ 3 surviving kids and desided all 5 kids were hers! Refused to let the other two in the same area. I worried about the smallest getting enough, but ended up pulling the two does because the new owner wanted to bottle raise, after a few days everything calmed down and now mom #3 feeds her two plus the other kid, and mom's 1 and 2 feed mom 2s kid. Everyone seems to be happy, so I'm leaving them alone. (and mom 3's bigger kid has learned to slip in w/ mom 1 and 2 are feeding the other kid and steal some sips, but they kick him off if they catch him).