Do I have to now split property with the grand daughter in PA?

Ok - just to clarify - your parents owned land as a tenancy by the entireties; they added you as a joint tenant with a right of survivorship. Father then died and your mother added her granddaughter, correct? Do you have a copy of this new deed and was it recorded? Since your father died, there was no tenancy-by-the entireties any longer. Rather, you and your mother owned as joint tenants with right of survivorship. I would need to see the deed (assuming this is in PA), but its my belief that your mother was able to do what she wanted with her share including conveying it to a third-person like the granddaughter or adding her to the deed. In such case, your interest is really not affected - you still own an undivided 1/2 interest in the property. Its just that the granddaughter now owns the mother's share. I assume that the real property is located in PA. If not, then you need to talk with a real estate attorney in the county/state where the land is located. Many register/recorder of deeds' offices are online nowadays and if they are it is easy to search for deeds. Whatever your mother said does not count - it matters only what was in her will, if she had one, or what was on the deed. To confirm exactly the ownership of the property get a copy of the deed where you were added as a joint tenant with right of survivorship - search under your parents' as grantors or grantees or you as grantee. Then do another search with the granddaughter as grantee or with your mother as grantor to see if any subsequent deeds pop up. If they do, look at the deed? Was it drafted by a real estate lawyer? If so, then you probably have to share the property. If it was not drafted by an attorney, get a copy of it and pay a real estate attorney to review it and get an opinion as to whether it is legal.