It was too cold, really, to open up any hives, though I did pop the tops off C/D and A to see if I could use the 20 oz. of syrup left from last time (I was quick and used a nuc migratory cover, so no critical amount of heat loss occurred). I was chagrined to find that in both cases that the feeders could not really accomodate any more syrup, though a single bee was feeding in C/D. I'm sure that B could have used another 20 oz. at least, but it was too cool (and breezy) to risk opening up that hive up.
I'm being an optimist and deciding that the full feeders are a sign that A and C/D have enough stores at the moment - I hope the feeders don't freeze before they discover what I left them, though. Nothing to do now but wait, I suppose, and do what puttering there is to be done.