I honestly never heard if that breed before! But if it's a domesticated mallard family duck i think they shouldn't go far away... Just stretch their wings(wich i a appreciate about birds myself)... But if you're concerned about them flying away you should consider clipping their flight feathers(wing feathers). Look it up there are lots of useful articles do you have any pics for us ?
They are sooo cute! You have one female and tow males(i made a little search on those flying ducks), and you might want to consider getting rid of one of the drakes as they will fight on the one female!