We went through this last summer... we had a bonded pair of sows and one of them died pretty unexpectedly. We got a younger sow (we watched her in with her littermates and she seemed not be an aggressive one, which was part of our criteria for choosing her. We didn't want to stick two 'queen bees' together!) We quarantined her in a separate cage in a separate room for two weeks. After that, we put the cages where they could see and hear each other and let them get to know each other from a distance. When we introduced them, we took them both out of the cages and let them meet each other on neutral ground... introductions actually went really well since I think Linney (our first pig who lost her friend) was REALLY lonely on her own. She was popcorning all over, she seemed so happy to have company! However she would not accept Sundae in her cage until we scrubbed the whole thing down with vinegar and rearranged the bowls and pigloos and made it 'new.' At that point they moved into the same cage and we really had no issues... my six year old daughter says they are 'BFFs forever!' LOL! Good luck with the introductions... if you know you have a bit of a bossy one to find a friend for, I would just try to find a friend who doesn't have those tendancies herself.
