It does take time for everyone to get sorted when you bring in new ones, best thing is to keep them side by side with fencing so resident ducks can still go about their business as normal but slowly realize the 2 next to them are there to stay it really helps make the newbies get use to everything too and no one gets beat up. It shouldn't take 6 months. more like a week. At night you can put the 2 new ones inside the duck house in a large dog crate so that way they are still protected but safe for the night.We are a bit concerned come spring, when we want to bring in 2 more ducks for egg making. Last time we did that, we had a dry spell for over 6 months, lol