Sounds mad, but johnnyboys misses, has trained her pet ferret to retrieve. . . .
But i don't think it would work in the hunting field.
I have a jill, who if she is near the exit, will drag them out, but usually they get stuck and she just kills them.
Best you can hope for really with kits, is a ferret that smashes them quick and drops them to move after the adults, in these cases a ferret that stays with its kill is a pain in the arse, as you will forever be digging to kits, however at the same time, a ferret that kills and moves on can be a pain if it kills quick, as you never kno