Bethe,
What a treasure and what a pain! I would scan the nitrite negs (and then burn them) and pack the safety film in a cooler, as suggested. The cooler will simply maintain the temp within a certain range. As you say, they lasted this long with no special treatment. The cooler then becomes a portable file as well, keeping them together. If there is room, and you've weeded out the nitrite negs, you might put some of your own excellent negatives in with them- keeping the whole mess together for the move.

I guess New England has seen the last of ou for awhile, huh? We miss you. Good luck.
Whitey