Other guinea pigs with pregant mums

Question
we acquired two young guinea pigs a fortnight ago
and it turns out that one of them is most likely to be pregnant.  They are definitely both girls
and I would like to know if they need separating before or after the birth.  Is it OK to have another female in the cage with the mother and her babies?  Also, is it possible to tell how far through the pregancy she is?  She very round and
I can feel the babies move sometimes. Her bump has become noticably bigger in the last few days.  She has two very noticable 'lumps'.  Thank you for your help.

Answer
Hi,
 Yes it's okay to have another girl in the cage. She might even act like an auntie to the newborns, She will also keep them company. If you leave her in there while she is giving birth the other guinea pig might even help open the birth sacs or she'll stay out of the way.
      You can tell when she might have her babies. When she gains more and more weight then you'll no that she is not to far away from birth, She should get a shape like a football and when it's about time to give birth the lump will seperate and she will have them before you know it!!
                           Blair