When 2 pigs have pups at the same time, will they care for each other's?

Since I have two pigs who will be giving birth any time now in the same cage, all kinds of things are coming to my mind...

I'm wondering what might happen once all the pups are born - will both mothers tend to all the babies? Will they nurse each other's pups? If they both happen to give birth during the night or while we're out of the house, do you think it will be obvious which babies belong to which mother, or will they just kind of "share" the mothering of all the babies?

If something were to happen to one of the mothers, do you think the other sow would take care of and nurse both litters?

One of my girls appears to have only one pup as far as I can feel...if something were to go wrong and that pup did not survive, would she likely try to take over one of the babies from the other piggie's litter?

I've read that other sows in a herd will often act as "aunties" and help out with the babies, but I haven't seen anything about what usually happens with this kind of situation when they are BOTH expecting!