Do you know which are muscovy? If not, you're going to have a bit of a time of it, but it should be okay anyway. Here is what I would do:
Candle the eggs regularly so you get a good feel for how they are developing. By Day 25, eggs that will hatch on Day 28 should be nearly completely dark inside except the bright air cell in the large end. You may see *some* veining, but mostly you'll see dark. You may be able to see the baby pushing against the inside of the membrane, or possibly even a little bill in the air sac. Eggs that look this way are ready for lockdown.
Your muscovy eggs will probably not be that developed. You will probably still see a lot of veining and the embryo kicking around in the fluids. Those eggs won't be ready for lockdown yet.
If they are all ready for lockdown, great--go for it--you've got mallard derivatives. If none are ready for lockdown then great, keep candling daily until they are--you've got muscovies.
If you've got a mix, you're going to have to make some judgment calls. My approach would be this:
Take them all out of the auto turner (if you're using one). Raise the humidity into the 60s, but not much higher. Place most of the sources of humidity on one side of the incubator, and put your locked down eggs on that side. Mark them carefully so you don't get confused. Place the remaining eggs on the opposite side of the incubator in a styrofoam egg carton propped securely at a 45-degree angle.
Three times a day, raise the humidity as high as it will go by adding water through the vent holes (you can use a straw or aquarium tubing for this). Quickly but carefully open the incubator, prop the egg carton to the opposite direction, close the incubator.
Your first batch will hatch around Day 28, but may still be in the bator as late as Day 30. As soon as they are done drying out, remove them to the brooder. Remove all the gunk and shells from the hatch, remove the sources of humidity, clean the incubator quickly but well (don't bleach though). Return the remaining eggs to the bator and continue to turn until Day 32.
Then lock down your remaining eggs and go.
Good luck. Sounds like a complicated hatch, but I'll bet you can do it.
