I don't think it is as long as you get to know them very we'll.
For example:
You should be able to go up to them without them screaming at you!
Not really needed but maybe once you get to know them hand feed them
If you don't want them to fly or run away clip their wings but if they've gotten attached to your silkies they shouldn't be leaving anytime soon…
If they don't leave, you will need duck feed to lure them in so they stay longer as well as feeding them so they don't eat the chicken food but don't starve!!!
I hope your ducks stay!
Wish all the best :cd