Give the cat to make her lactate?

my cat just gave birth about 6 hours ago, her breasts are VERY swollen, but the kittens cannot get milk from her. she is laying and trying... I tried to stimulate them with a warm washcloth, but the milk is not coming out. Unfortunately she gave birth while I was out, and had them in the box that already had a cat with kittens in it that were born a week ago... Im worried that the other mommy may have eaten the placenta and she doesnt have any of the hormones to get the milk flowing... I can tell she is uncomfortable.. she is trying... I even let some of the older kittens at her first since they suck harder and nothing is coming out.. they walk away from her and look for their own mother... the littleest ones are nursing off the first mommy too, and she is miserable.. I tried locking them in a carrier alone together but the babies are crying for food... what can I do? is there a home remedy that can stimulate the milk to come out?