So...
This was me a couple days ago: https://www.backyardchickens.com/threads/freaking-out-day-40ish-muscovy-eggs.1631169/#post-27852071
I put 16 eggs under one of my muscovies on May 20th. When I candled on day 7, all 16 were developing so I know I'm not off on the date by much. Unfortunately, most seemed to die late in incubation, leaving 6 still moving around when I posted. They pipped internally shortly after that post, but two died before pipping externally. After that I made safety holes on the remaining 4.
Yesterday, mom violently opened one of the eggs, flung the duckling around, and then swallowed it whole right in front of me while I was changing the water. Horrifying! She started opening this egg and I quickly rescued it and the remaining two eggs. Brought them inside, put them in a makeshift incubator, and the other two pipped and started zipping. This one had its head on the wrong end of the egg and was getting sticky/shrink wrapped near the giant hole momma made, so I have been doing an assisted hatch over the course of yesterday and this morning. I left the others alone because things seemed to be going well...
Woke up this morning to find that the other two had zipped partially and then died

It has been hatched for a couple hours and is working on fluffing up. Now I'm trying to figure out what to do with it. Raise it alone in a brooder? Give it to mom and hope she doesn't eat it? She is a few years old but a first time mom and now I don't trust her very much.