If your in the US and your Scovys are young you may not get a broody till next year. when you say shares the nest do you mean sitting on it or laying eggs in the one nest. 19 is alot for a first time broody anyway. I'd take out the cleanest and incubate them in a bator if you want ducklings now but remember winter means ducklings will be inside for a long time. Explain what you mean by it's been over a week now. It's really hard to know when one is going to get the broody bug .