Our first question was, "Did a predator (such as a neighbor's cat or dog, a Cooper's hawk, or even a bobcat) get her?"
That seemed unlikely because the babies were still all present and unharmed (as far as we could count - its not easy to get an accurate count! The quail babies move en masse, with a sort of "flow" that makes it hard to discern one baby from the other). Usually, a predator would target the babies, which are easier prey. This did not make the "predator theory" very plausible.
We decided that she must have become gravid again, and went to lay more eggs (with another male). We have many male quail in the yard, fighting daily over the females, so this explanation made the most sense.
Overall, Super Dad has done a GREAT job! He keeps the babies moving through the yard, a behavior that most likely prevents predators from reliably finding where the vulnerable babies may be. The babies themselves have adapted well, and form a tight-knit group that follows Dad when on the move, and lays together in a cohesive unit when he's allowing them to rest. The picture on the right is Super Dad assembling the babies in a safe group near the edge of tree cover, but still in the warm sun. As you can see in the photo to the left, the babies are quite content to just lay down, preen themselves, and wait for the next command to move.
And I'll leave you with my final picture: here he is!! Super Dad!!!
With the babes content in the sun, Dad gets the good perch, calls out some territorial "chucks" and watches over his chicks. What a guy! To hear examples of his territorial call, click on this link, and scroll down to the "male aggressive call". This is also the sound the males make when the fight over the females during mating season.