Why not just purchase a grey smooth breasted gander and breed to your white female or vise versa.
Here is a very nice grey smooth breasted gander I have and he carries the Buff gene so he is split for buff because he has buff coloring coming through his grey feathers. This fellow is a sweetheart and come right up to you for romaine lettuce and grapes. He is a nicely balance gander as well. This is what you should be looking for. Not other breeds to make mutts.


Here is a very nice grey smooth breasted gander I have and he carries the Buff gene so he is split for buff because he has buff coloring coming through his grey feathers. This fellow is a sweetheart and come right up to you for romaine lettuce and grapes. He is a nicely balance gander as well. This is what you should be looking for. Not other breeds to make mutts.