Basic information since I've gotta run:
The babies will be getting enough nutrients from mummy so long as mummy is fed right. Now she's with you, drown her in pellets (high in calcium alfalfa-based pellets if you can) and give her and the babies alfalfa hay mixed with your normal hay. This will help the babies to grow big and strong as alfalfa is high in calcium. Also, drown the piggies and mummy in lots and lots of hay to help support mummy. You'll also notice, depending on the babies age, that they will also eat whatever mummy has.
Weigh the babies each day - that's how you can tell if mum is feeding them enough or not. If they are gaining weight, you don't need to intervene and mum is doing great without you. You can, however, handle them daily anyway to get them use to people and make then friendlier.
Is there any way you can tell how old the babies are? Remember that the boys should be separated from mum and the sows at 3 weeks when they sexually mature, sows (girls) can stay with mummy after this period.
I don't know of any products that are safe to be used on pregnant sows or babies that will get rid of mites or lice. I've heard conflicted reports; some people will dose the mum and not the babies and others say that the danger is too great and to wait until either it's a confirmed - and bad - case or until everyone is old enough.
Here's a good source of information of babies:
http://www.guinealynx.info/reproduction.html
Note: pictures or it didn't happen!! rolleyes