I found reference to an organization called Netherland Israelitisch
Sick Fund. Given that one of the ancestors had been born in Holland,
maybe they were members.
Hope this helps a little.
SF Bay Area
On Wed, Apr 3, 2019 at 6:09 PM Madeleine Isenberg
I found this acronym, N.I.S.F., inscribed above the Peh"Nun on stones