Adverse Possession Survey
I believe that this is an issue for an attorney to handle. There may be survey work involved, but IMHO this is a legal matter.
Surveyors should be equipped to recognize fact patterns that support unwritten rights and transfers of title. We can even educate ourseleves on how to walk owners through solutions that are uncontested. When we start advising people in adversarial situations or attempting to adjudicate things we have crossed a line. I've made more money cleaning up crap solutions by surveyors than you can imagine.
Montana is unusual when it comes to AP. I suppose you could say that about most states, each one is different.
Montana has a short statute of limitation time for AP: 5 years.
Yet even with the short time it's often said that Montana is a difficult state to win an AP claim.
Paying taxes is one key there, in other states it's a throw away issue.
I try to stay at arms length dealing with AP, I advise my clients to get a good attorney and discuss it with them, I would surely do that in Montana.