Oklahoma inherited mineral rights

Looking for direction to turn… My grandfather left me in his will undecided minerals totaling 640 acres from his original family homestead which initially was divided etween him his brothers and his mother… He bought out all family members later on from what my dad and I remember from my grandfather and grandmother telling us… His will was probated through court with appeals to it made by his brothers and was upheld as written and filed in court… I was contacted by a landman about a lease on a non leased section of land… According to their title company they showed by county land taxes I owned 40 acres of the family minerals in the quarter section they were looking at, but according to my grandfathers will I own the full 160 acres of minerals in this 1/4 section… Can someone tell me what or how I figure out where to look or turn to…

Thanks a million…

In Texas the mineral rights are sold with the land unless they are specifically retained by the seller in the deed to the new purchaser. Go to the title company that the land man got his info from with his referral. If they will help, get copies of the past deeds (chain of title) and see if when your grandfather "bought out" the members of the family if the minerals were mentioned in the deeds to him. Looks like the minerals were a part of the property that was conveyed when the property was initially divided up...