How long has Beanie been back at home with your other two cats? When I introduce a new cat(5 so far) it takes a couple of weeks for them to get used to each other. Keeping Beanie in your room is a good idea right at first, as I do the same with my cats. Then I start letting them out 2 hours the first day, 3 hours the second day, and so on. They will have their fights at first, but this will evenually start to lessen as each day the time out is longer, and pretty soon all aggression will be a thing of the past(an occaisional spat is normal for all cats, mine are the same way). you just have to be patient and let them do their own thing, but just keep an eye open to make sure there is no serious injuries.
Good Luck
Jenn