I recently got 4 adult ducks and it was a very different experience adding adults to the flock rather than 6 week old ducklings. I kept them in a separate run for a few days so they could all get used to each other. On day 5 I let the new ones out with the flock- there was a bit of fighting between the drakes- but nothing seerious. I locked them back up again after about 20 minutes later after staying and watching them all. The following day I let them out again- The faught again for about 2 minutes and all was well. They have all been together ever since and all get along very well now. They do still have a social pecking order like chcikens- but not so strongly developed. You may find they will sort each other out fairly quickly - but I would suggest you have a separate area for the new ones for week or so.
