You need to make a nest box for the babies to help keep them contained and together. One of the most common causes of death for young infants is exposure (gets too cold).
A shoe box, a small rubber maid, a clean litter box are all good make shift nest boxes. It needs to have sides high enough to keep the babies from wandering out and low enough for mom to hop in.
Put 1-2" of safe shavings (not cedar!) in the bottom or another soft litter. Then fill the box with lots of hay and make a fist sized hole in the middle of the box.
Transfer the babies and whatever nest she built into the hole in the nest box. Make sure the babies are covered with lots of fur.
If mom is fussy about you messing with the nest, let her out for some play time while you transfer the babies to the nest box.
Having the nest box will also allow you to check the babies easier. You can just pull the box out of the cage instead of having to check on them in the cage.
Mom will only feed the babies once or twice a day. She will stand over top of them and they will feed from below. At the same time she should clean them up a little bit. For the rest of the time, she should ignore them. She will not lie with her babies like a cat or dog will. The babies should have nice round bellies if they are being fed.
Can you post pictures of her current set up and of the babies? We can then make some suggestions for you and tell you if they have been fed yet.
-Dawn