I've taken about 30 animals home from a shelter to "socialize". My Rule of thumb is LEAVE THEM ALONE.. First I'll bring the new guys into the house in the carriers, set them on the floor and allow everyone to get a good sniff of each other, while I ignore the entire group. While this is going on make sure that the food & water dishes are filled, and add an extra dish for the newbies. After they are well aware of eachother, and the first major hissing is finished, usually 20-30 minutes, open the carrier doors and again LEAVE THEM ALONE. Let the new guys look around, the residents sniff around them. Talking to everyone is ok, but otherwise see rule number 1, LEAVE THEM ALONE.. not only can you get bit by a scared newcomer, even your own babies can forget who you are if you grab one unexpectedly from behind, so LEAVE THEM ALONE... after everyone has explored the new surroundings and the new arrivals, and have settled down and are approachable, show the new guys the food dishes and littler boxes. once is usually enough, cats are very smart, then LEAVE THEM ALONE. This process which really doesn't require human involvment can take a few hours or up to a day or two at most... But I've found it to be a very reliable and stress free way to introduce new babies into the home, and trust me, I've introduced plenty foster kids. Cats being the sensitive animals that they are will pick up your emotional state during this, so TRY TRY TRY to remain calm, act as though everything is OK, and above all, LEAVE THEM ALONE.. they will decide when you can join in the fun, or the fighting... If you have any questions, I have instant messengers and my screen names are in my profile.... Good Luck...