Legal Question in Intellectual Property in Texas

Probably not. However, there is a chance she might try to qualify for standing to sue by establishing herself as a bona fide common-law wife. A key question then would be whether your son and she "held themselves out" to the public as a married couple and whether they engaged in various transactions as husband and wife. Unless she's got a bundle of cash to pay an attorney to pursue this for her (which would probably depend on the value of the property in question), then she's probably just bluffing. In any event, I would sit back and wait for her to make any step before deciding to do anything.