Yes. Even though you are not on a physical lease Pennsylvania has abolished self help even in situations like this. She needs a court order for what she did. You have a right to bring a case against her
DISCLAIMER: Matthew Solomon is licensed to practice law in both the State of Pennsylvania and the State of New Jersey.This answer based on general legal principles and is not intended for the purpose of providing specific legal advice or opinions. This answer does not constitute the establishment of an attorney-client relationship.
As a tenant, you have the right to remain in possession of your rental property until or unless a court orders you to vacate. Your sister can not change the locks and kick you out. Explain this to your sister and if she fails to relinquish possession, seek the assistance of a lawyer.
If you liked this answer, please rate it "HELPFUL" or "BEST". You can contact Michael I. Werner, Esq. for further detailed answers at 412-904-5305. **DISCLAIMER** Michael I. Werner, Esq. is licensed to practice law in the Commonwealth of Pennsylvania. His practice focuses on Pennsylvania Landlord-Tenant Law (representing both Landlords and Tenants), Pennsylvania Estate Planning, Pennsylvania Real Estate, Allegheny County Property Assessment Appeals, Allegheny County Real Estate Tax Appeals, and General Business Matters. This answer is based on general legal principles and is not intended for the purpose of providing specific legal advice or opinions. This answer does not constitute the establishment of an attorney-client relationship. It is always recommended that you consult with an attorney prior to taking legal actions on your own.