Unfortunately, leaving Mom and the babies undisturbed most of the day didn't work. There was no evidence Mom had joined the kittens. In the meantime, Meg and Sue had strongly suggested, in off-blog correspondence, that I get Mom and kittens into closer quarters and consider starting bottle feeding and stimulating elimination.
I replaced the warm rice snake and called the vet's office, as I'd promised I would. I briefed vet tech Jenn on the situation. At this point, Jenn got a hold of Doc Andrew. He was concerned that trying to wrangle Mom into closer quarters would freak her out/piss her off more and suggested moving the box out of the crate. We all agreed I should start bottle feeding tonight if moving the box didn't do the trick and they immediately offered to take the kittens while I'm at work tomorrow and Thursday (Friday starts an 11 day vacation).
I woke up after a quick nap (at this point I'd kill for 3 or more uninterrupted hours of sleep... how new parents do this for months is beyond me!) and decided that, since Mom seemed to feel safe under the bed, I would cut down a box so it would slide under the bed, then tent the sides with a sheet. I figured this was a good compromise, creating closer quarters and not risking freaking Mom out more (LOL... I checked email afterward and Judy had the same suggestion! Thanks, Judy!)
My sis came over to help and we quickly weighed the kittens. They'd lost weight (.2-.3 oz each) confirming Mom wasn't feeding or feeding enough. We put in another warm rice snake, slid the box under the bed and hoped for the best. Soon we heard kitten mewlings all the way upstairs, in the kitchen. Then, suddenly, the mewing got really, really loud... and then stopped abruptly. We hoped that meant the kittens had plugged in to Momma.
I gave it a few hours and went down again. I heard a scurry as I descended the stairs. Mom was in the window and started yowling when I got to the bottom. I ignored her and checked the kittens. The box didn't seem "Momma warm" as though she'd just left, but the kittens felt warmish. It was hard to tell for sure, but one section of the towels seemed to be mashed down more than the rest, the "comfort towel" that I'd arranged around the kitten pile was askew and the box had some debris that I was pretty sure hadn't been there before, since these were fresh towels. And I saw no evidence of pee or poo, which is good. I cleaned up the debris so I can use that as a means of checking again.
I'd bought a nursing kit today and, after warming the kittens with a fresh rice snake, tried to bottle feed them, just in case. None of them would take the bottle and all of them fussed at me but good. Their fussing was more vigorous than when we'd weighed them, so I thought this was good. The fuss brought Mama down under the bed again and she gave me the hairy eyeball throughout - probably a good sign. I checked the flow and I'm pretty sure it's good, so I'm hoping (praying, pleading with the good Lord) that this means the box under the bed worked and they're dining with Mom.
I'll check in a couple of hours, just in case I'm wrong. If I'm still unsure, I'll replace the snake with a heating pad (the extension cord had been hiding from me, earlier). In the morning I'll weigh the babies. If they've gained a bit, I guess we can safely assume they're feeding. If not, I think it is safest to take them to the vets for the day.