I have four and personally I think the younger they are when introduced...the easier. Puppies can not take the temptation to play with another puppy. I will say all of mine prefer small size puppies to larger ones. Eventually Toby will accept the new pup at your aunt's and yes it's likely he'll want to establish his role when he gets a sibling.
__________________ Deb, Reese, Reggie, Frazier, Libby, Sidney, & Bodie |