Adverse Possession: Sorry Axx Greedy Neighbors

My question involves real estate located in the State of: Texas
My father bought 25 acres back in 1974. I had a surveyor come out to cut out some acres for me on the north end. The surveyor found that the northeast corner pins were 50 feet short of where they should have been, a mistake by the original surveyor. Neighbor to the north had bought land three separate times from the same estate. First two purchases have metes and bound that coincide with dads original and their third purchase the surveyor went to the fence. Total area in dispute is .55 acre. we made the neighbor aware of problem and well what we thought were good neighbors were very sorry ones. They have threatened adverse possession claim. The fact that the original survey stakes were incorrectly placed along with the fence we thought was in the right place, Do they have an AP claim because we were totally unaware of the problem. we have been paying taxes on that strip since 1974 when we bought. Any help is greatly appreciated. Thanks

Adverse Possession: Sorry Axx Greedy Neighbors