Broody hen hatching duck eggs?

[eking121121]

Hi everybody, I recently purchased 2 Cochin/Pekin gens and one just went broody! The lady I bought them off never let them go broody, but I let it incubate one egg they had laid which I washed off (I was originally planning to eat it), and I know that without the protective layer it is likely to go bad. Anyway - our neighbour has muscovy ducks, and she might have a few I could buy, but the problem is that muscovites take 35 days to hatch, which us a LOT longer than chicken eggs. Also, if the washed egg did hatch, how likely is it that the hen would abandon the duck eggs? I have an incubator and brooder box, but we might be away when either hatches. So, basically, it all waters down to 2 questions: would the hen abandon either if the bad egg somehow hatched, and would a hen sit on muscovy duck eggs for 35 days?
Thanks.

 

[eking121121]

The hen has been sitting on the washed egg for around 3 days now