Okay so my theory did not really pan out, so I quarantined the mother duck and she has been sitting on the nest all day. I noticed she did that yesterday too, but the males ripped her off to have sex with her, hence the quarantine. This will also stop the other hens from laying eggs in her nest too. Hopefully I will see some chicks hatch but we will see. I also think one of my other hens has a nest because she was missing this morning and then popped up later on, which she did when she was sitting on her nest earlier this summer.