Reverse ownership lookup

My family recently started receiving offers for interests we acquired through inheritance thanks to a wealthy TX industrialist. We had no idea that his estate owned these interests until acquirers began making offers on our interests. Does anyone know how to do a search by name such that it cross-references TX counties? (and elsewhere) with the RR Commission or County Clerk etc. to see where he may had a a billion dollars worth of W. TX rights.

Would his will have been probated? Maybe the lawyer who wrote it or court that did the probate would have such a list.