oh boy would i bawl my eyes out if that happened to me. If they do come back i advice keeping them in netted pens, OR clip their wings.
If they did make it where they were going someone might have taken them and clipped their wings, i know if i saw such gorgeous ducks in my yard i'd snatch them up
If they should miraculously come back,they will be so wild you will be lucky if you can shoot their wing tips off, much less get close enough to clip their wings..
semi wild ducks do not fare well against predators..
My 2 mallards met up with a wild flock living at a near-by lake last year. I know I should have clipped their wings but they were so beautiful flying loops around our property. They flew back and forth throughout the summer but took off in the fall. They actually brought a wild female back with them one day. I hope they don't return because I've read that wild ducks are more likely to carry disease and can infect your flock.