FOUND HER!!!
Found the broody that is hiding her eggs. Along the rock-face bordering the property and the road, under a cedar tree.
She'd managed to knock some of the eggs out of the nest, too.

Amazingly, only one was cracked. After maneuvering myself along the rock, I gathered the eggs and put them back in the nest, and gave her some food.
The cracked egg didn't look too bad, just a chip really, and I covered that with the only stuff I had which was wood-glue, and put it in the incubator with the rest. Lets hope their little trip didn't scramble them.
Estimated hatch would be by mid-week next week, or up to the weekend. We shall see. I may attempt to move her... If she does succeed to hatch these out, and the ones from my lost broody also hatch, I'm going to try to give her those chicks.