Cat or dog replacement milk would be preferred to Moo milk.
Make sure to clean them well after they eat some, in my experiance with kittens and raccoons, the babies are all about crawling through the food. Wipe them down witha warm wet washcloth maybe, and be SURE they are in deep bedding to stay warm. You might try putting one of the other rats in to see if they will wash them and cuddle them. It's a longshot but it would save you having to clean them. They will still need the feeding though, a 3 month old isn't likely to suddenly develop milk! lol.
GOod luck!
Wolfy