My mallard hatched three ducklings in April. Last summer we rescued a Black Swedish Duckling and added it to our small female flock. It ended up being a drake and he was over breeding and was aggressive with my Mallard. So I got her a mallard friend but she wasn't too friendly with the new...
Personally from my experience I would be cautious bringing in a smaller female with a large drake. It may work well for you. My situation is different because I have a small flock with a heavy drake and a mallard.
I started out with an all female flock. It started with my mallard (who had an...