Sounds like DD has a good handle on it. Vicki is the one breaking the agreement, and right off the bat, too! Not a good sign. Unless it is a rare situation where DD and the other girl can send their checks in and let Vicki swing when her check is short, it could be difficult to force
Vicki to do anything. She's already got her stuff in the big room(s) and if they only have a verbal agreement about how to split the rent...
I would be really angry at Vicki--sounds like she deliberately concealed her actual rent limit during all the discussions. She could have easily said she would take the middle room so as to meet the rent limit imposed by her parents. And if this is just an unexpected cash-flow crisis this first month, she should have come to her roommates with abject apologies, asking them to cover her for this month and she would pay them back AND make sure she set aside the proper rent for next month in advance. Does she really expect the other two girls to pay extra for the whole year, while she has the best room, in contradiction to their agreement? It makes her seem very irresponsible and untrustworthy. I hope if I was DD or the other girl we would get together and confront her about this.
And, to be honest, I wouldn't want to demonize her--I remember having my first apartment with someone, and our parents were paying for it and had no experience with what it would cost. My roommate's mom kept complaining to her that she spent too much money when it was her turn to buy groceries, for example, and my parents didn't care, so my roommate kept trying to put all kinds of expensive things she wanted on the grocery list when it was my
turn, and then only buy the minimum when it was her
Not cool, but we were pretty dumb about a lot of stuff, I have to say.
Vicki needs to understand that she made a commitment to pay $X in rent per month in exchange for the biggest room. She needs to find a way to meet that commitment. Or she has to give up the biggest room, but only if one of the other girls can take on the added expense of having the biggest room--if neither DD nor the other girl is willing/able to pay for the biggest room, Vicki might be stuck with it, and she needs to step up and take responsibility. If that means giving up $10 of fun money per month, or talking to her parents to rearrange the money from them (+$10 for rent, -$10 for clothes, for example), or picking up cans on the roadside to sell for extra cash, then she needs to do that.