It is difficult to say how old they are exactly. Thankfully, piggy babies are able to eat normal food although most switch to a mainly solid diet during the second week of their lives. The weaning process starts soon after when mum is increasingly discouraging the babies from drinking; babies are usually considered to be weaned and self-reliant from about 3-4 weeks onwards.
Yours may profit from a bit extra depending on their weight. If they were able to get some sow milk (either from their mum or another nursing sow), they have a much better chance as it is especially the first milk that is heavily laden with antibodies to build up their immune system.
Here is more information on baby care:
https://www.theguineapigforum.co.uk/threads/after-birth-and-baby-care.109389/
https://www.theguineapigforum.co.uk/threads/sexing-separating-baby-boars-and-rehoming-babies.109391/
If you have got a pair of sows, it would be good to try them on neutral ground and see whether the sows will accept the babies; that will give them social security and guidance that they need.
Illustrated Bonding / Dominance Behaviours And Dynamics
Please weigh them. It would be good if you opened a support thread in our pregnancy section once you know the weights, so we can advise you better according to how much support they need.
I would also most strongly recommend to sex/double check them to make sure that they are all girls before you start naming.