bucksmith
Did you lock the doors?
The box would of came from one of the original family houses. Either Flanders, NJ or Long Branch, NJ.OMG! Those pics are priceless! Where/when did your cousin find the box containing the negatives?
To me, the sartorial clues peg this as happening at an organized event (airshow, barnstorm, etc). I'd start looking for what aviation events occurred in the area in question back then.
I’m no historian, but I was under the impression most post WWI barnstorming wasn’t organized.