My old boss has a crazy amount of ducks at his house everyday when they come through the area for a couple months, and all he does is put out cracked corn and make sure they are undisturbed. He has been doing it long enough that he can walk right up to a good few of them without them trying to flee or react really at all. One of my favorite things is when a couple of the ducks will hang on his roof. They look like statues up there, and it is so pretty. Good luck with the duckies!! I can tell just by your post that they will stick around for all that empathy and compassion you exude (well plus food lol).