I had a smidge of good luck with the NH State Police. I submitted a tip about a year or two ago, and the detective called me right back to ask for the provenance, which I gave. I never heard back after, but at least it garnered an initial response. So to say they aren't interested in civilian help is not entirely true, but I'm thinking it's mostly true and only one way. Like, if I had asked questions, of which I have many, he might not have been forthcoming, but at least he reached out.
I also emailed the team doing the research to ask for more specific information, but never heard back.
My two main questions, which I think may help a lot, are: (1) were the MC's ancestors the issue of Thomas Mitchell and William Livings's marriages, in that is she as genetically related to their wives, too? And, (2) how strong is her genetic relationship to the Spiers, as that name comes up a lot in both the Mitchell and Livings descendants.
So if anyone knows those answers, please let me know.
Full disclosure: I'm probably not using the right terminology but I'm just an amateur.