Five fewer guests could enjoy his concoction-
Perhaps larger portions for the fifteen?
I found the little slip of paper with this recipe in some of my mother’s recipes.
I don’t recall my mother ever making any potato salad
Do you have recipes on little slips of paper? Sometimes they are stuffed in a cookbook.

I don’t know who Elmer Newkirk is but he must have typed out his recipe snd shared it. Have you ever heard of putting a peeled apple in potato salad?