In Texas, a person who is asked to sign an affidavit of heirship is most likely in a situation where the decedent (person who has died) has died intestate (didn't leave a will). So, if this situation occured in Texas, I might expect that there probably isn't a will to look at in the first place, or else something else had gone wrong. If I suspected there was a will, and that I would inherit under the will, I would consider taking steps to assure that the will was probated (submitted to a court and validated) and followed.