Well, she looks chocolate - was the KC her father? What she should have going on from that combo is that she is a chocolate mallard, and she should be split to dusky and also split to harlequin (snowy).
So, should she breed with the ancona drake, is this drake a black ancona? If yes, anconas are genetically one copy extended black and one copy wild type (mallard). So half the babies would be extended black, and half would be mallard. All the sons would be split to chocolate, and half the babies will be split to dusky and half split to harlequin, since they will inherit it from this female. The Runner Gene, aka pied, which is what gives the ancona the white patches, is dominant, so all the babies would be partially pied.
With the buff drake, things will be interesting. Buff is a chocolate color, so all the babies will be chocolate. Buff dilution is sex linked, so all the female babies will be buff and the males will be split to buff. I cannot say though if you'll be able to tell the different at hatch, since I've never done that breeding myself. Buff is a dusky color, which is recessive, and this female should be carrying it, so half the babies should be dusky. The other half will be carrying it. Buff orpington is also a blue color, so half the babies will be blue, too. And of course half will also be split to harlequin, inheriting it from the mother. So, lots of possible outcomes with this cross.
