How many guineas do you have? How old are they? I started with 4 lavender guinea hens, now have only 1 left. Each spring they would begin to lay, until sometime in early summer. It seemed that somebird would decide on a nest spot, and then all the rest of them would add their eggs there. They would lay 'em & leave 'em for a few weeks, then somebird would decide to go broody on them. I'd find her clamped onto the nest at nightfall. We'd have to pry her off (making one angry guinea!) to put her in the pen for safe keeping overnight. Then I'd fill in the nest and cover it up so they wouldn't use that spot again. The next day somebird would have to stake out a new nest spot.
Since I don't have a cock bird I would collect the eggs for eating. They're deeeeeeeeeeeeelicious! Extra-rich because of all the bugs & seeds they eat. But the shells are super hard!! You have to crack them on the counter, or whack them with a knife to open them.
I could collect the eggs from the nest, leaving one or two marked with a permanent marker to encourage them to continue to use the nest. My interference didn't seem to bother them, I could do this in plain sight of them. Anyway, guineas don't have a sense of smell.
We got good at listening for the guinea's special "egg song", a sound they'd make only when they were on the nest. Sort of a high-pitched "wheee-whee-whee-whee". When we'd hear that sound we'd try to trace its source to find the guinea nest.