Should I give her her own room?

My daughter is 8. She is beautiful, smart, caring, and loving. She also has Bipolar disorder. She yells at her sisters (both younger 5, and 3). I have them all sharing a room, hoping that the interaction will help her behavior. She lies, but I honestly believe it's not because she's trying to be a... well... a bad word.... All their toys are in our 3rd room in the playroom, we've had it since she was born (the playroom) because even as a baby she was moody and as a toddler she would have major tantrums for no reason. So now, at 8 she is getting worse. I'm going to ask her therapist also at her next appt, but I was wondering what other parents, or other individuals who understand her moods, thought too. I don't see her "disorder" as a disorder. Because it is who she is, her emotional difficulties are just part of her. That being said it is very hard in our family, my husband has medical (gastro) issues which leaves him upset and moody also. I have anxiety and depression although my medication is helping me handle my own issues (every day is a struggle). Fiona, (my oldest) also has severe depression which we have been working on for about a year, but since that has not been helping we are going to get a consult for anti-depressants.
So, my question is this.
Should I give her her own room and put half the toys in her room and half in the other girl's room? With her emotions getting more and more rapid, she explodes at them more often. I am concerned that they will start to question why she gets away with things that they don't (neither of the other two are as emotionally volatile as Fiona) and they will try to act up based on her actions.
So, that's my long story. What do you think?

Thank you,

Samantha