Multiple nests in one pen?

[sourwoodmuscovy]

Hello, I am new at raising Muscovies and have a question.  I have one drake and 5 hens in 40' X 40' outdoor pen.  I've set out 7 nesting boxes.  First one started filling with eggs.
So, if I am lucky to have several hatches, do I need to separate the hens / broods / nests before they hatch?  The duck book I have says hens will start killing one anothers ducklings!  Is this true?

Thanks for your help and shared experiences.

SourwoodMuscovy (Vermont)