Territorial ducks

[Featherlove23]

How do I introduce new two week old chicks to 6 week old. They won't let them get close, one of the ducks hissed at the chicks, which I can understand. They didn't grow up with these two chicks and haven't bonded. But once they are old enough they will be in the same coop so I want to get them comfortable with each other but don't know how to go about. I've never had ducks before, only chickens. They grew up with the two in the pen with them the other pictures are the 2 week old chicks.

 

[nuthatched]

They need to be introduced slowly, over a couple of weeks, on either side of the fence.