I’m not an attorney, but from a Landman’s perspective:
If the mineral rights were placed into a Trust (on the property records in Caddo County), then successor Trustees should be able to act for the Trust, and the Affidavit of Heirship only serves to confirm that the original Trustor/Trustee is deceased and Co- or Successor Trustee(s) are then authorized to act for the Trust. If the act of getting it into the Trust was a function of the probate in another State, then a local-to-the-lands probate (or foreign probate) may be needed to enact that provision of the probate upon lands in a different state.