My advice would be to gently hold and pet them a lot so that they come to think of being touched as a friendly thing, not an aggressive "chasing" or "get away" thing. I spent so much time sitting quietly with my little angels when they were ducklings but I didn't try to touch or hold them (I always let them approach me) and now that they're grown, even though they are friendly towards me and always come running over (and quack loudly for me to come to them when they see me across the yard), they are skittish about being touched, even super gently. I think they think of it as being pecked, the way the dominant ducks peck at them to make them move out of the way. That said, I only had ducklings once, so I don't have proof that touching them a lot as babies would have definitely resulted in adults that like being pet and cuddled. Next time I have ducklings I'm definitely going to try it though!