Although you and your sister are of record title owners of a condominium given you both and the property has subsequently been rented, it does not matter if your sister is not named on the lease or did not sign it provided that you did when you owned it. The lease between the tenants and you is a valid lease with your sister as well.The reason is that under "agency laws" in this country, in all likelihood your were representing your and your sister's interests when the lease with the tenants was entered into. You as a co-owner of the condominium agreed to lease the proeprty. Your acts are considered the acts of your sister under the law.In the event the tenants fail to pay rent or do some act warranting their eviction, your sister as co-owner of the condominium can initiate eviction proceedings against the tenants.