How old are your current ducks?ill give you a short story on the 4 i have now (2 male and 2 female) they were hatched together they were raised together they were sold together they always are right next to each other. if that ratio of 2:2 is bad i will not be able to help that. from my expiriences in the past the ducks that were raised together stayed away from ducks that were raised at a different time male or female except one time when one flock had only 2 males left and 1 flock had only 1 female left. the 2 males battled for the female and when one won him and the female joined together and the female was fine until she got taken by a racoon. (i now let my ducks sleep in the chicken coop) so as far as i know my 2 male and 2 female flock would stay away from my flock of 3 male and 7 female. also if the gender is still a problem would adding 2 indian runners or welsh harlequin females help enough to keep my current order. also if that was to work which one should i get and explain why (also if you are saying i should get an indian runner tell me which color)
p.s. sorry for that run on sentence
Unless you are housing them seperately, it is unlikely that the 2 flocks won't mix. Even if they don't mix, you have too many males. Instinct will override anything else.
Experts, Dave Holderread, John Metzer, recommend 3-5 females PER drake. I go by what they recommend as they have been doing this for far longer than anyone I know. You can successfully keep pairs but not necessarily in a flock situation. Domestic ducks don't bond into pairs.
If you want to get the males that you stated then you need to have 15-25 females total.
What is your purpose for getting so many different breeds? If it is to hatch purebred ducklings they will all need to be seperated during breeding season so probably Jan-June for you. Pure ducklings sell much easier than mixed, though sometimes they don't sell at all. If you don't want ducklings, why not just get females?
I cannot tell you what breed you should get. You have breeds selected that are all over the range in personality, egg laying and size. Research what breeds YOU want and what colors you want. But again, think about what is best for the birds. Even in the worst case senario.