Co-worker issues – how to deal with a know-it-all who interrupts everyone?

my friend works in an office with six other girls – one girl gets under everyone's skin periodically and they are looking for a way to deal with her without causing problems. first off she is married to one of the union officials, and when she is angry at someone will make statements such as "well i am so&so's wife and i will have my way". (mind you she is in her 50"s). she does not help others and can be down right mean, unless of course she is in front of a boss- then she acts as though she had offered to help but they refused her. if one girl is speaking to a boss and she walks in the room she will interupt the conversation just by starting to talk to the boss as if the girl is not there. what she doesn't realize is that no-one cares for her and even the bosses talk crap about her behind her back to the girls – they know how she is but can't do anything about it because of her husband. i feel bad for them as this woman's moods change throughout the day and really put a strain on how things get done. they have tried just ignoring her but that seems to cause more difficulty, they have moved her desk 4 times and no matter where she sits she eavesdrops on peoples conversations, interrupts people, does her personal business at work and butts in giving her miserable opinion to anyone in earshot. also there are 2 girls in particular who she seems to need to prove that she is better to bosses and union officials so she says insulting & untrue things about them to other people including other union officials & her husband. they have tried politely addressing the interupting issue and gotten screamed at then she won't talk to them for a while and there have been a few occasions of loud arguments but nothing is ever resolved. any suggestions?