This was not planned, but I realized afterwards that it worked out this way:
Take a 4 gallon stock pot. Add the frozen carcasses of roast chickens past that you've been saving in the freezer (4, as it turns out). Also add the frozen chicken backs you've also saved from home-trimmed chickens past (4!).
Add one package "chicken leg quarters" purchased for added meat (skinned and fat trimmed). As it turns out, the package has 4 leg quarters (which consists of a thigh and drumstick each).
Add 4 bay leaves, 4 celery stalks, 4 small white onions (peeled and halved), 4 carrots (peeled), 3 parsnips (hah!), a large bunch of parsley, a handful of peppercorns, a sprinkling of kosher salt. Add enough water to cover (filling most of the 4 gallon pot, but this won't yield nearly 4 gallons of soup after all the solids are spent and removed)
Bring to simmer, let go all day long.
Delicious, but I'm amused at the repeating 4's...