Surprise Inheritance.... Next Step?

A family member was recently contacted by phone by someone offering to lease/purchase mineral rights that she was unaware she owned. Research showed that she had inherited "an undivided one-fourth interest in all of the oil, gas and other minerals in and under ...". This excerpted from a 1941 Mineral Deed.

The property description is "Section 23, Block C-15 Public School Land Reeves County, Texas ... which contains 683 acres". We also found a 1960 ten-year lease to Shell Oil that was apparently never developed (per my read of the RRC GIS map).

At this point we are not much interested in the offer (very low compared to those referenced on this forum) and our next step will be to get the title changed to reflect the new ownership.

We would welcome any additional forum recommendations. Thanks in advance.