You know what's odd about this whole thing?
Now that the sicklies are gone, the rest of the flock is chipper as can be, foraging around the yard and seem to be happier than they've been in a while. Probably has a lot to do with the sunshine, but we had sunshine the last couple of days & they didn't act like this. I think the two chickens that were in pain were stressing out the rest of the flock. DH refilled the hole where we were going to put the carcasses, but the rest of the girls have already made themselves at home in the loose dirt and have spent the afternoon sunning and dust-bathing and diggin' out worms. All 6 remaining girls are sitting together, including the 2 that just came this past week.
I feel a lot better now. I know we did the right thing, not just for the two that were suffering, but for the rest of the flock, as well.