Excellent tip, leaving her up there but make it so the chicks can't walk off.
Looks like too many eggs, you need to collect all in that nest, candle them, and give back the batch that seem the closest to each other in age and discard the rest or put rest in incubator. If you can tell which eggs are her own, these are probably the best bet for leaving as the other eggs could be "same age" or way younger and never will hatch in time with the original eggs when these hatch.
The average hen can cover 10 eggs well, there are hens that can cover more or less but 10 is a good general number. In the end, no eggs should be visible at all from under a broody hen- if any egg is visible, that is too many eggs. What above said is very true, too large clutches can potentially end up successfully hatching only one or 2 chicks due to the eggs getting killed in 'succession'.
If you can, seal off the whole section so the other hens can't fly up there and bother the broody hen too.