For Anyone reading along, I am finding some answers on my own research.
As for the 7.5 acres, that belonged to the deceased cousin. I found Oklahoma law that states:
§84‑213. Descent and distribution
A. Prior to July 1, 1985, if any person having title to any estate not otherwise limited by marriage contract, dies without disposing of the estate by will, it descends and must be distributed in the following manner:
http://livingtrustnetwork.com/estate-planning-center/applicable-state-laws/intestate-succession/oklahoma-intestacy-laws.html
Now her dad died before the Mom had even inherited the minerals. The landman is telling me the minerals are then split between the Mom's and Dads relatives, equally. But, According to that article, it would go to the Mom, or moms family or the relative with the closest family heritage.
Fifth. If the decedent leave a surviving husband or wife, and no issue, and no father, nor mother, nor brother, nor sister, the whole estate goes to the surviving husband or wife.
Sixth. If the decedent leave no issue, nor husband, nor wife, and no father or mother, or brother, or sister, the estate must go to the next of kin in equal degree, excepting that when there are two or more collateral kindred, in equal degree, but claiming through different ancestors, those who claimed through the nearest ancestors must be preferred to those claiming through an ancestor more remote
B. Beginning July 1, 1985, if any person having title to any estate not otherwise limited by any antenuptial marriage contract dies without disposing of the estate by will, such estate descends and shall be distributed in the following manner:
e. if there is no surviving issue, parent, issue of parents, grandparent, nor issue of a grandparent, the estate passes to the next of kin in equal degree;