New duck question.

I have a female Mallard....who is now 1 year old. A friend of mine has a male she wants to get rid of, because he is mounting and killing her hens. When I bring him home....do I need to keep him in a crate for a week or so....just so he doesnt fly away, and take my little Waggles with him? She also has a white duck she wants to give me....with the mallard. Not sure what it is...but she doesnt want ANY more ducks. Can I keep these 2 in a crate together for a weeks or so? Or will I even have to? Will they stay near the pond with my other ducks? I dont want him to fly away with my Waggles. Help!!