I have a big cage, and I have one sow guinea pig, and she’s pregnant. She has a giant giant cage, and I was wondering if I could get another sow, and put them together?
You'll ofc have to do bonding but for sure. I've done non littermates before. Its always worked out pretty good. Besides once but thats another story, the bonding wasn't done properly n they we're males.
You can put non-littermates together, but you can't just put a new pig into another pig's cage -- they'll fight for sure. You need to introduce them in a neutral place (see http://www.guinealynx.info/introductions.html for how to do it). Then put them into a thoroughly cleaned cage that has nothing in it that smells anything like either pig.
Another option might be to just wait until the pups arrive and then keep any female pups to live with mom. You'll have to separate any male pups at 21 days of age.