Two sisters co-own a house that they inherited twenty years ago. They came to an agreement whereby they would share certain maintainance expenses for the home, but one sister would have sole possession of the home to use as her residence while paying rent to the other sister. At various times the sister receiving the rent has asked for an increased amount, and the sister in residence went along with the requests.
She recently demanded a more significant increase and the sister who lives in the house thinks it's too much money. Does she have the right to unilaterally increase the rent?

