I have four ducks, two blue swede males that are about 3 months old, and two campbells (1m 1f) that are about a week younger. The campbells joined us when they were about two weeks old. They all get along well together, I just can't have three boys and one girl. I plan on keeping them in pairs. The obvious choice is by breed, since they have been together since birth and are closest to each other. My biggest concern is if I keep the campbells together, will that cause problems when they are old enough to breed? I believe they are related, possibly different dads, but I don't want to deal with birth issues if they do mate and have ducklings. Any ideas? I'm sad to give them up, but they are backyard ducks and having 3/4 of them chowing on grain with no possibility of eggs just doesn't "fly" with my husband!