They are beautiful! Really pretty birds.
I read that a blue fawn has the genetics of blue (N/n+) plus chocolate. Since we're talking about a female, she only has one gene for chocolate. So ch/--.
Then, (maybe) lilac is different in that it has the genetics of silver (N/N), which I think of as splash in chickens. Plus the single gene for chocolate, ch/--.
I have no idea which genotype your birds have. Sorry I can't be helpful at all there. I simply don't know the difference in what they look like. But if we want to try to figure out what colors you would get from crossing to a blue drake, you would figure the blue X blue, or blue X silver (splash, in my mind). Then figure in the chocolate gene.
It's a little complicated, especially considering that chocolate is sex-linked. And that college genetics classes are far, far in my past! But here's what I come up with. Assuming that your blue drake isn't carrying chocolate, of course.
If the females are blue fawns, you should get mostly blacks, blues, and silvers, with an occasional chocolate, blue fawn, and lilac female.
If they are lilacs, you should get mostly blues and silvers, with an occasional lilac and blue fawn female.
I think.