I didn't check thousands of profiles but so far I couldn't have the option to add a friend.
Maybe we can't do that through the new auctions system ?

If we can, then yes indeed there are merged servers but probably only for that.
Like in asso for example, we can play or loan a player from a team of another server but doesn't mean we can buy him.

So far, I see I can't make a nego offer to a friend from another server.