
My bitches are never interested in a whelping box, until they have whelped! :-)
If they have a favourite chum, that's fine. I only seperate when they take a particular dislike to one of the dogs. A bit like us, they get tetchy with hormones raging! And you never know which dog they will take exception to.
I found years ago, that trying to get them to spend time in the whelping box, just stressed them out. Yet, once they've whelped, and I move the pups into it, they settle just fine.