True for person and location you don’t need a qty.
But for other where you might be working with items or groups you might want to include more than one.
In my case I was making a fleet of ships and wanted to include more than one of the same ship to the fleet.
So if we were in Star Wars you might want to have like 3 X-Wings or Tie-Fighters but since you can only select an item once and there is no qty for a relationship it makes it hard to create groups of items.
Maybe have a 4th selection - Person, Location, Other & - Groups?
Thanks