I find it easier to separate the duckling that might be showing problems since if you have five ducks eating a bowl of treats there is a good chance one might not be getting any while the other is getting a lot, if that makes sense. Giving it to the other ducklings would not hurt them though.
If you start giving them the B complex on a daily basis there would be no need to continue the nutritional yeast, more doesn't mean better, they can only absorb so much, the excess will be expelled with their waste.
Going to pick it up from TSC in a few hours! Thank you so much again