Seth posted a practical list building problem in The reunion problem. The problem is to locate all the grown kids who have attended Camp Arowhon during its 75 years of operation. His suggestion was to begin with the known members of the targeted group and to enlist their aid in locating others.
Along those same lines, I suggest that the parents, and even grand parents or other family members of relatively recent Camp Arowhon participants are more likely than other people of being alum. Assuming that Camp Arowhon itself is cooperating in the project, it could notify the parents of this summer’s crop of kids of the upcoming reunion, which I assume is a fairly clean list, and work backward in time.
I suppose I’m suggesting that it might be useful to work with someone who already has a list, even if it is an old list.
Plan for the clerk in charge of the list to pucker up and mumble something about privacy considerations.