Premie care w/ two litters

Hi, I'm hoping I can get a bit of advice. To begin, we have four indoor cats, about six months old. Four days ago we brought one of our local feral queens (Fluffybutt) into the house because I was fairly sure she was in labor. She had a healthy litter of five. All is well, they are gorgeous. We had her closed into the bathroom to keep the cattens (our older kittens) away from mom and young.
The day before yesterday another queen (Skitty) had her kittens under the house. She also had five, but they are very small. I'm fairly sure they are premature. They have very little hair on their legs and their skin is all wrinkly. We've brought her and the babies in, and currently have each mommy and litter shut in a reasonably sized carrier.
Now the problem is, I've been able to stay home with them for a few days to make sure all is well and to let them out to have a scratch in the litter and eat, but I can't continue to do so. The bathroom is the only room with a door in the house, so I can't seperate them by room. I'm not sure about leaving them out of the carriers in there together.
So,do you think it would be ok to have both carriers open in there so moms have access to the box and food/water? In addition, does anyone have any advice on any extra care that premies need? They seem to be nursing ok, and I've kept the bathroom at a warm temp, but I'm not sure if there's anything else I should watch for or can do to help.
Any assistance would be greatly appreciated.

I would be weary of letting 2 cats with litters together in the same room, unless you knew they were bonded before the births. The stress of having 2 cats together could be enough to cause some pretty bad things to happen; lack of kitten care or fighting to protect their babies. Make sure the carriers you have are large enough that momma cat can distance herself from her babies if neccesary and can turn around and not step or lay on them when locked in there. You could open the carriers in rotation, one cat out one day, the other out the next day,and make sure when you have them locked up you can atleast hang food/water dishes on the door. Just be sure that you are not going to cause unnecessary stress to these cats. Especially the momma with the preemies, newborns are fragile enough, preemies have alot more going against them. You should get some good info from the folks on here, they are very helpful. Goodluck