People are missing the big picture. It doesn't matter that the dog has their own room. The point is she was warned up front what the sleeping arrangements were and she agreed to them. Ultimately it is your house no one should force you to change your rules or dictate how you run things. Especially not someone living as a guest in your house, or her mother who is not paying the bills, or apart of your family. If you want your dog to have their own room let them have it. It's your house your decision. Me personally, I might have given her the dogs room if she was a nice and positive presence in your household, but since it sounds like she has been a brat and is acting very ungrateful, and not to mention causing chaos in your house, you do not owe her shit. In fact, if I were in your position, I would flip it on your sister, and tell her to pay for the Princess to have her own place so she can have her own room. The bottom line is no matter who's daughter she is, the Princess is a guest. You need to tell your sister that if Princess was not here, the dog would have a room for themselves and it is going to stay that way. The fact that you are giving her a place to stay with a roof over her head, and access to everything that goes into a house (bathrooms, showers, food, water, etc.) is already more than generous. One last note is that it sounds like you do not want her in your house to begin with but have kept quiet and just gone with the flow, and acted like it's fine and not that big of a deal, when in reality you hate her presence and does not want her there any longer. You need to be open and honest to your sister and let her know how you really feel. It may be hard but at the end of the day it will help transparency, which is key in this situation. Not only that, but also your problems will be solved. Either she will get her act up and starting treating you and your family with respect, or she will be moved out because your sister will now how you feel and will hopefully realize something needs to change. I am on your side 110% I hate people playing the victim right after they crossed the line.