Hi, Cyndy -
TennisDaze and Christine have very interesting points and questions: How did your cousin have the right to place everyone's interest into a trust?
Online Records for Culberson County appear to only be available back to about 2009 and those records will only be the Real Property (now Official Public Records), not Probate or any other records. Unless your cousin or the Landmen or company(ies) making offers to your family can provide you with some sort of documentation, you will have to perform your own research at the County Courthouse(s) in order to determine title to your interests.
And before you or any of your family considers selling their mineral rights, I would advise that you allow me or someone else look up what is happening in the area first.
I have run across several instances where less than reputable companies and people have been trying to buy people out not only for much less than the interests are truly worth, but at times also knowing that the potential Sellers have royalties in suspense from wells that have already been drilled (In essence attempting to buy people out using their own money to do so - sometimes at an obscene profit).
And unless you or any of your other family members have a dire need for the money, such as a family medical emergency or somebody to get through college, I strongly advise that you DO NOT SELL. And if you just want a little money to play with, then only sell a portion - 1/4 or 1/2 or so - of your interests.
You should always consult an experienced Oil and Gas Attorney about things like this. Wade Caldwell is a frequent contributor to The Forum and very highly spoken of. If you need the names of a few additional Attorneys to consider, accept my offer to become A Friend on The Forum and I will provide you with contact information on a couple that I can personally recommend.
Legal fees might cost you a little money, but the peace of mind of having qualified and experienced representation is worth every penny. You could request that the other family members share in the expense.
Hope this helps -
Charles Emery Tooke III
Certified Professional Landman
Fort Worth, Texas