Nutmeg is chocolate mallard. That's it, it's just chocolate on mallard base. Blue fawn is one blue dilution gene on mallard base.
Nutmeg is more brown. Lilac is a combo of the two.
I think it might end up being lilac or lavender, yep :) Of course it would be lilac mallard or lavender mallard, since that one is definitely mallard patterned.