The observed behaviours:
(a) I recently wormed them with a levamisole product in their water. As directed I removed their water source overnight, so they were thirsty when I put the medicated water in with them. All 8 birds can't fit around the waterer. I found all of them were drinking except my Sussex, who was obviously quite anxious to get in there but only managed to squeeze in after a couple of them had had their fill.
(b) Yesterday I took them some watermelon rinds and held onto them while they pecked off the remaining pink goodness. My double-laced LF barnevelder (largest bird in flock) deferred to the light sussex, who is always the first to try new foods. But even when it was obvious most of them were enjoying it she still hung back. She's also lost her long curved tail feathers in the last couple of days, and I'm thinking they may have been removed by her flock mates. I checked them all for signs of lice/mites a couple of days ago and they looked fine.