Ive tried letting my girls sit on call duck eggs, and will never ever do that again. It was such a waste of eggs. There is no way to moniter the humidity, and ducks need more humidity than chicken eggs. All of the ducklings ended up getting shrink wrapped in their eggs.
I was gonna try the peacock thing with my silkie hen...but I think the eggs is almost bigger than her. lol
My silkies had no trouble covering 3-4 peacock eggs and they hatched them very well. If your hen is small maybe just 3 peafowl eggs.
I'm pretty sure she could only cover one. She is so tiny. I swear some days she shrinks. I was looking at her outside today thinking about the whole peacock egg thing. I'd say her body is about the size of a can of soda. lol