Since you should not include a ss# on any publicly filed document and an "executor document" is not a form recognized by Texas law, I'd say you're not off to a good start using this will kit. I have no knowledge of the quality of the website's wills, but when I get "home cooked" wills, they invariably have problems. Please see a lawyer.
Assuming you have probated the will and been named executor by the Court, you can evict your sister. You will probably need an attorney to help with the eviction. A grandchild does not have homestead rights in her grandmother's house.
Here is the test: do any of the attorneys offer to take the case on a contingency. If they do, you have a solid case. If they don't, they're just flapping their gums. Talk to attorneys who specialize in wrongful death actions -- there are many in Dallas. I think you will find that they are interested in a consultation with you, at no charge. If after the consultation, they want to take the case, great. If not, then that is your answer.
We call our specialties different things: some call this elder law, probate law, estate planning, guardianship, etc. The thing to look for is experience with someone in handling guardianship matters at Court and estate planning services for the will and powers of attorney.
You will need to retitle, but the executor will need to deliver you the titles signed by the executor and a copy of the letters testamentary to do this. You will not be able to get your annual registration without updating the title.
If the will can't be probated, then your aunt can't be executor. A person is only executor if appointed in a will that is probate and the court confirms the appointment. If you are an heir at law, you may need to initiate probate proceedings, so contact a probate attorney in the County where your Grandfather lived at the time of his death to discuss your options.
You need to open probate either by probating a will or opening administration, if there is no will. Probating a will is very quick, but the administration can take longer depending on the heirs and other facts. You should start as soon as possible to be able to get the royalty checks started again.
You should hire a lawyer to contest the will or file something in probate court right away if the will hasn't been offered. You present a case with interesting potential. The will is not automatically invalid but your Dad's medical records may establish that he lacked the ability to execute the will (testamentary capacity) or that he was weak and his relatives took control over his desires (undue influence). These type of cases are very fact specific. You need a lawyer in the area where the...