I finally found out where Macaroni has been laying her eggs. I found her beneath the raised sidewalk on the south side of the house, about 6 feet from the edge of the pond. I noticed that I hadn't seen her all day and I thought I'd peek between the cracks of the sidewalk to see if I could find her. Sure enough, I could see her sitting quietly. About an hour later she was off her nest and I went over to quickly count how many eggs she was sitting on. I counted 16!
If she hatches even half of those eggs she'll have 8 babies and Macaroni's sitting on at least 14 eggs that we can see, so half of those would be 7. I've read that you should expect 10% of duck eggs to not hatch. So at the most I could expect 27 ducklings!
I never saw any of this coming and I'm really excited about the possibility of adding more hens to my flock and having some nice young duck in the freezer. Keep your fingers crossed!