Better explanation of my payment question

Lease granted to Expl Co. by "A". Exp Co drilled gas well & pooled "A"s interest.

"A" started receiving royalties. Years later "A" sold property (including minerals) to "B", but "A" continued to receive royalty payments.

One year later, "B" sold to my family (including minerals) but "A" is still receiving royalty payments.

"A" never notified Expl Co that he had sold minerals.

Neither "B" nor my family knew of the interest in pool until a month ago.

My family has been the owner for the past 5 years.

Any chance my family can recoup any of the payments that were made to "A" when they should have gone to my family?

There is a chance to recover the payments because A was unjustly enriched. A received something he/she wasn't entitled to.

Collectability may be a problem.

I would contact an attorney to pursue this.