My new cats aren't getting along!!! HELP!!!!?

I recently got two persians. I already have a cat, hes a year and a half and the persians are about a year older. As soon as I brought them home, the one went hiding under the stairs and I can't seem to coax her out. The other one is a little skitish too, but not as bad. Will she ever come out from underneath the stairs? I'm afraid she wont even come out to eat or use the litter box. Any tips so get the persians to get along with my other cat?????