I think you have three dark phase Silver Appleyards and one Welsh Harlequin (I suspect a drake). You might like this link about Silver Appleyards:
https://www.backyardchickens.com/threads/silver-appleyard-ducks.647080/page-2
https://www.backyardchickens.com/threads/silver-appleyard-ducks.647080/page-2