Around 4:30 Monday afternoon, the continuing NOSH were easily refound. But of the original 4 apparent females, today there were clearly 3 females and one male.
The male and one female were engaged in some serious but brief head-bobbing, which ended all too soon (and without the predictable conclusion) while I was there.

One full breeding plumage male Ruddy Duck was swimming nearby with RUDU females. No sign of the Hooded Merganser group, though we walked the perimeter of the pond.