Raising Wood Ducks -- Help!!

I'm looking for tips/tricks on raising wood ducks. I have wood duck boxes behind my house and one of the hens got eaten by a raccoon the night before her eggs hatched. I collected the ducklings and eggs and put them in our incubator. Of the 16 eggs, 13 hatched. It's currently day 7, and so far I've lost four ducks. I know wood ducks are notoriously difficult to raise, but so far they seem to be doing really well, compared to some of the past years. (In past years, hens have been eaten and only a couple eggs end up hatching...and the ducklings died hours after.) However, I don't want this pattern of fatalities to continue.

Right now, I have all the ducklings in a large box lined with newspaper and paper towels (I change it 2-3 times a day). I have two heat lamps over one end of the box. I got them a chick waterer, and have been filling it with pond water and distilled water. I started off feeding them ground up high protein dog food and duckweed from the pond water, as I had nothing else in the house. Yesterday (after I lost 2 ducks) I started feeding them Nutrena Nature Wise Chick Starter Grower feed (18%). I've heard really good things about Mazuri Waterfowl starter, but I can't find any near me and anything I order online will take a week to get here. Should I order some anyway?

They seem to be eating really well! I sprinkle the food on top of them and that seems to prompt them to eat most of the time. They alternate between a few minutes of napping and a few minutes of chowing down. However, the one I lost most recently stopped eating near the end. I sprinkled food in front of it and it did nothing, it just laid there with it's head nodding pathetically onto its breast. It wouldn't eat, drink, or move. I realized there was nothing more I could do for it, and so I held it while it died (the other ones kept stepping on it in their home). I have no idea what caused this death. Any ideas?

I've heard ducks are particularly susceptible to niacin deficiencies, so tomorrow I'll be getting some brewer's yeast to add to their food. Is that a good call? If so, how often should I add it to their food?

Any advice is welcome!

Please help! I think there's another one that stopped eating and I don't know what to do.

This might be a little late, I'm really sorry, but if you still have them have you tried the duck starter from Mazuri? You may find the wood ducks take to it better than the chick starter.  Also, have you tried adding some of your food mix to the water?  Lots of ducklings seem to gravitate to feeding in the water before they'll consider eating on dry land.  Think about what a wild duckling would do. They are led straight to the water where they begin feeding. Also try and smear wet food on the walls or sprinkle it on them. You can put them with other ducks like mallards to teach them how to eat.