This one managed to pick up a massive swarm of ten ducklings, in part by collecting a few strays that hatched in a nest by the front door. She's proven herself an outstanding mother, moving her brood all over the property in search of food --- and, after nearly two weeks, not losing a single one of those ducklings. Call her the "duckling magnet."
A few days ago, I found a single very young duckling running around the vineyard unattended. It most likely hatched earlier than a duck's other eggs, and wandered off the nest while she was waiting on those other ones. I tried adding it to the "duckling magnet" brood, but the other ducklings were simply too much larger; the new one couldn't keep up. But, remarkably, another Khaki (whose eggs likely didn't hatch, but whose hormones were likely still elevated in a motherly direction) grabbed onto him. He now follows her everywhere, and she's been doing an excellent job with him.
And, finally, this is the oddest collection of ducklings. Where this Khaki (the one on the far right) picked up this brood, no one knows. But they've been together for weeks now, and are thriving. Sometimes it's best not to ask too many questions, and just let nature do what nature will do.