I'm sorry to hear that your family is drifting apart, so to speak. Unfortunately, generations now are raised to not value family. I believe that that is part of a wider effort to destroy the family unit.
I had to look it up, Thanksgiving is a week from now, Thursday 23rd, yes?
Is there any chance of having a little talk with your siblings about getting your nieces and nephews more interested in family history? Maybe a couple of people could tell some interesting stories about some family members living and deceased? If everyone brought some food as contribution and you supplied the venue, perhaps it could turn out to be a reasonably fun day, and something the younger crowd might look forward to next year?
Maybe someone could start writing something up as a larger ongoing project?