Is it hard to add 2 bonded females to 2 already bonded females?

[Deenanicole08]

I really want to get these 2 girls the the Eaton County Humane Society, even though it's almost 2 hours away, I feel that I just need to save them and I think about them everyday several times, and I check petfinder to see if they are still there, and they've been there quite a while. I was wondering how hard it would be, if I could convince my mother to let me get them, to bond them with my 2 already bonded females if it's even possible. I would imagine there would be quite a bit of fighting.

 

[Percy's Mom]

If your cage is big enough, I wouldn't think you would have much problem at all introducing the two pairs. Make sure you introduce them in neutral territory and try having a bunch of food out during the introduction to distract everyone. Sows tend to be much mellower about their herd growing than boars.