How many hours a day is sufficient for a Muscovey duck to sit on her eggs?

[MuscovymamaG]

Hi, I hve two quires 1st how many hours a day a Muscovey duck is suppose to sit on eggs.
Secondly if she is not sitting properly and spent most of her time in nurturing other chicks which I bought from market is it still possible to get ducklings from her eggs.
She sat on them for like 15 days with full intensity but after i bought these new ducklings she is roaming around with them all the time. Kindly suggest something I desperately want her to hatch some eggs.

 

[JacinLarkwell]

You'll need an incubator. 23 hours usually is the minimum since they do get up and eat and poop, but they need to be almost constantly sitting

 

[MuscovymamaG]

I don't have one

 

[MuscovymamaG]

Already wasted 40 eggs because of these abounding attitude of other Muscovey ducks now I guess again going to face this loss