They are very pretty!
Theoretically yes, there would be no problem with them breeding, as long as the males are able to get the job done, what with the size difference.
As far as colors, if they are ancona pattern, then, according to Holderread, they should genetically only be heterozygous for extended black. That means they should be able to produce babies that are both black and also mallard based. They should also have two copies of the Runner, aka pied, gene.
So the babies would be gray partially pied and black bibbed partially pied.
However, your females almost look like they might be magpie pattern, not ancona pattern. Magpie is a possible outcome from breeding two ancona patterned birds together. The only difference between magpie and ancona is that magpie is homozygous for extended black. So if that were the case, all the ducklings from this cross would be black bibbed and partially pied.
If you're interested in reading more about the genetics of mapgie and ancona, you can read
this article written by Dave Holderread
