Breeding crested Magpies

I just got into ducks four weeks ago and I love them. I got four ducklings from the local mennonites. The only info they gave me on the breed is that they are "black and white". One of them has a white tuft on his head now so I'm guessing they are crested magpies. Anyway, out of the four of them only one quacks and the others peep. So I guess that means I have 1 female and 3 males. I wanted the ducks for eggs so I would like more than one female. Can I breed her with her brother just this one time? I would find someone else with magpies to breed my female with but the problem is that I live on an island in the pacific which is a 7 hour ferry ride to the mainland. The mennonites are the only people with this duck breed and I'm guessing if I got a male from them it would be related since thats where I got my ducks. I know someone else who has muscovies but I would prefer to stick with this breed. my second question is can I breed my male with the tuft on his head with the female? She doesn't have a tuft. I have heard that there can be problems breeding two ducks who both have the tufts.

Thank you to anyone who took the time to read this. Your expert advice is greatly appreciated.

Tiffany