How can I convince my mom to let me take the office as my room?

[keri]

Ok...

Me and my sister share a room. My mom has an office downstairs that she used to use alot but now she barely uses. I am trying to convince my mom that I should have her office as a room because she barely uses it. My little sisters wears my clothes and MY UNDERWEAR! and ruins them. She is really messy and always throws fits like a two year old even though she's 11. If I tell my mom this she'll get all defensive over my sister so what should I tell her so I could get the office.

[AkosuaM]

always sleep on the couch and cry or complain of a back pain every time you wake up

[AkosuaM]

always sleep on the couch and cry or complain of a back pain every time you wake up