I own a property in San Francisco Ca. and am renting to a family member. The property is managed professionally via a realtor firm. A "No Pet" clause was included in the initial contract. The contract was signed. A few months after, a request was made for pet. I informed the tenant to please adhere to the terms and conditions of the original contract. The tenant then obtained a letter for a Psychiatry doctor about the tenant's mental illness disability: social anxiety and coping with certain situations. Her doctor has prescribed an emotional support animal. The property is leased by my uncle; however, has his daughter living at the residence. Nothing was said about a pet prior to signing the lease. The cat is currently at the residence. What legal recourse do I have? Thank you.