When will they start to fly?
I have a grown one (lost the other three over time) will they be okay with the one adult one when I get them old enough to release?
I keep keets in a big coop until they are too big to squeeze through my chain link and netted run. I have had bad experiences with a keet "escaping" and being eaten within a day by hawk/coon/fox.
Also, keeping them inside gives guineas the idea that here is their home. Guineas are not like chickens and homebound; one day I watched nine of my guineas leave our land and "walk on down the road" never looking back.
Once they are growing good, let 'em go.