She's doing a bit better but still not great. She's drinking a lot which is encouraging, so we have a water supply with nuti-drench and electrolytes. She hasn't vomited that we've seen since last night which is also really encouraging. She also seems to bit a tiny little bit more active than yesterday. We switched her sick-buddy to Juniper who is an excellent example and seems to be encouraging Herman to drink. Herman is still spending a lot of time in her little box but she'll come out for a few minutes at a time, stretch, clean a little, stand in a corner, etc before heading back to box.
We filled up the bath tub and let the girls have a little swim for 10 minutes or so and then pat dried them before going back to the little duck hospital. We're trying to trick Herman into "eating" a duck slurry like you suggested so we have a very watery slurry of duck pellets and peas blended into a soup right next to the water for her and we're waiting to see if she will take some.
She got quite fat for winter so I'm not immediately worried about her not eating, but we want to keep her strength up so I may attempt to feed her with a feeding syringe if we don't see her eat anything in the next few days. We're having to pill her for her antibiotics so we're kind of doing sad-pill time anyways.
Situation is complicated by the fact that we're separating the boys and girls outside since the boys are being oddly mate-crazy for winter, but the girls and boys still want to be together so they're sitting on each side of the duck run complaining and our girls inside the house can hear that and get a little stir crazy (at least Juniper does).
I'll try to post some pictures and keep you all updated. Any other ideas or advice are welcome.