<human>: Could you distill the essence of the text into 1-3 sentences?

Hey, this is a question to anyone out there that can help. I live in Corvallis, Oregon. I currently live with six other roommates. In the town of Corvallis there are laws that say no more than 5 non-related individuals can live in a house without it being up to code for being a duplex, or something too that effect. So, to combat that situation, our landlord had 5 of the roommates sign a lease for a year, and two of us are "ghost" tenants. 

Well, one of our 5 signed tenants is wanting to move out of the house. She signed a 1 year lease, agreeing that she will live there. The lease is an agreement to pay rent in a lump sum, and not on an individual basis. The roommate who is leaving us is saying that the lease has no effect on her, and that she will take our landlord to court, saying she doesn't need to pay because of our current "illegal" living situation. 

My question is, is there anything we can do to stop this? Most of my roommates are too afraid to confront her, saying we will find someone ASAP too fill her room and supplement rent. I on the other hand find want our landlord to challenge her. What legal rights does she have in this situation? Will it end up being that if she takes us too court, that the two "ghost" residents will be forced to move out? Does anyone know how this might turn out... Any help would be amazing. I'm confused, worried, and angry.
<bot>: Too many people living in a house as agreed too and advertised by the landlord. One of the lease signers is leaving before the lease is over and expects too not have to pay during her absence. What can i do?