I don’t know how to vent sex ducklings but I plan on having another BYCer help me learn this spring. I tried once and I felt like I was going to hurt the duckling so I stopped.
I put my babies out when they are big enough to stay out of the adults way. I’ve never had them accept the ducklings. They are like high schoolers. But they do adjust eventually. I did have to put my drake in jail last year because he wanted to mate with the babies that weren’t mature enough. The babies and all females got along as long as the drake wasn’t around.
This was my duckling integration exactly. At 6-8 weeks they went outside. The females accepted them pretty quick as long as the drake wasn't around. The drake tried to kill one and then when older he was too rough when trying to mate the ducklings. So the ducklings lived with the adult females relatively peacefully (some squabbles over food) and the drake stayed in jail about a month. Now they all get along fine.