So glad the little duckling is starting to hatch and is making progress! It should have absorbed the yolk sac by now with zipping, but if it does hatch with some yolk sac not absorbed, you can put it back into the bottom part of the egg and hold it in a cup if you have one the right size to hold it upright, I have seen pics of it online of the "egg-yolk cups"
Also, don't fret if some umbilical cord is still attached to the duckling and egg, if it is brown, it'll just snap off by itself, and if it is red, it should turn brown after a bit and break off on it's own. But if the duckling struggles with it too much, even if it is still red, get some clean scissors and heat them up and give it a quick snip.
I did that when the second assisted hatch still had a bit of red cord attached, and it was pushing against the shell too much and I feared it pulling it's yolk sac back out, so I gave the cord a snip with the hot scissors while holding the feet to keep them out of the way, and there was hardly any blood as the heat sealed the wound pretty much the second it was made and the chick didn't even seem to notice anything other than being now free. The cord that was still attached fell off shortly afterwards after drying out.
Edit: Here is a pic of a yolk-cup, though using a tub. It should absorb the yolk sac within a few hours if it wasn't absorbed already.
but not near what you've been going through the last couple of days. I look forward to the new arrival and can't wait to see photos. Thinking of you today as you experience duck parenthood!
