How to raise Backyard Chickens: [CHICKENS-101] Buff's going broody

I have a mixed variety of chickens, don't know all the breeds. I do know that 2 of them are Buff's ... not hard to tell what they are.

All the chickens seem to want to lay eggs in the same nesting box. I built 8 boxes for 20 hens, but they use just 2 of them.

Sunday I noticed that the Buff was staying in the nest instead of going to roost. I have 1 or 2 roosters, so the eggs might be fertilized.

Since she went broody, the other Buff is in the nest next to her doing the same thing.

My egg count went from an average of 10 per day down to 3 or 4.

Are they causing the others to not want to lay eggs since they are in the prime nesting box?

Thank you for your help.

Allen