No need to remove Fluffy, as long as Fluffy is definitely female. Guinea pig sows usually make good aunties for another guinea pigs babies, it is only on very rare occasions that a sow will take issue with another sows pups. You will however want to upgrade to the double connected midwest setup sooner rather than later, the edges of the pups ears may get chewed if the sows feel overcrowded.
Baby guinea pigs, lactating sows, and guinea pigs under 6 months of age all require the same care, which only differs from adult guinea pig care in the sense that they require extra calcium for their growing bones (or milk), whereas calcium intake should be limited for adult guinea pigs to minimize the risk of them forming bladder stones. If you are already feeding young guinea pig pellets (oxbow and KMS are the only brands we recommend) then there is no need to do anything differently for mum and pups.
If either of the pups are boys they will need to be separated off from the girls when they are 3 weeks old, here is a page with images you can compare to
http://www.cavyspirit.com/sexing.htm . Don't worry too much if you aren't sure what genders they are, it becomes easier to tell as they get closer to three weeks (also male guinea pigs have a bone in their penis which can usually be felt as a firm vertical line under the skin if you gently rub your finger across the top of their genitals).
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