Lookin' goood! I'd love to see a photo of the albino in the 2nd photo after it sheds.
"The one who had a twin that didn't survive is very under weight - I'm not sure if I should force feed now or wait until post shed. Any guidance?"
I already mentioned that last year I was in the same boat that you're in. My outcome wasn't good, so you need to take that into consideration. Was it something I did or didn't do? Wish I knew for sure.
I think the key here in your case is whether or not it's weight is within the weight-to-length ratio of the others? In other words - is it also shorter in length? I use visual appearance & activity (actions, reactions, etc...) to gauge health. No doubt - visible bones signal "danger."
I would most likely wait another week or so before force-feeding, as long as it's not already skin & bones. I would also try feeding it live mice pinkies instead of rat pinkies because of the snake's smaller size and the possible intimidation factor that some live rat pinkies can give smaller, timid hatchlings.
I hope I don't insult your intelligence, but often times, putting prey items directly in front of (or on) some snakes will make them more timid & even fearful of it. But, you don't want to put it on the opposite end of the tub/cage of a coiled hatchling, either. I usually move the snake from it's coiled position to the opposite side of the tub & then place the pinkie where the snake was laying.
I think the more privacy, security, you can give it, the better it's odds of beginning to eat are. Wait a few days or so between feeding attempts.
Hang in there!
HH
-----
Due to political correctness run amuck,
this ol' hillbilly is now referred to as an:
Appalachian American

www.natures-signature.com