I have been summoned! Lol.
If the drake is Blue Swedish, they'll all be blue bibbed, silver bibbed, or black bibbed. You can narrow down mom on the silver bibbed ones because they'll have to be from a blue swedish OR the buff to get that other blue gene. Buff is actually a color that can include blue. And chocolate. And the buff gene. It's a complicated one! If your buff is a 'dark' buff and doesn't have blue, then she can't be the mom of any silvers. If she's a 'standard' or 'light' buff, she can be.
Male ducklings from your khaki hens will carry chocolate. Males from your buff hens will carry chocolate and buff. You can't see that, though, but they will pass it to half their sons and daughters when breeding.
Ducklings from your Rouen will only have one copy of Extended Black, and since it's an incompletely dominant gene, you might get some 'bleed-through' of the mallard pattern and color. Like this duck:
