June 28, 2020:

While to this day you still question the paucity of her inheritance.

The guy was a gazillionaire, owning acres and horses and tractors and herds. How does his long-lost daughter rate $100k and mineral rights?

Perhaps it was believed the mineral rights were more valuable than they turned out. For a time they generated $4k/mo in natural gas royalties, not an untidy sum.

Perhaps he didn't value her as highly as she valued him.

You can't know. They were secretive, and after all, you opted-out long before his death. What incentive did they have to keep you informed?