I only have two hens and they both lay their eggs in the same nest. We don't have a rooster (OH is a conscientious objector to crowing).
In spring last year one of the hens started brooding on the nest (she sat on it 24/7 whether there were eggs under her or not) so I got 6 fertilised eggs from a friend's farm and popped them under her, 21 days later two chicks hatched, but one only lived for 48 hours.
The other 4 eggs were broken in argy bargy of sharing a nest, typically when a new egg was laid by other hen on same nest.
My hen sat on her hatched chick for at least a month after he hatched and was a very proud and protective mother throughout. The chick grew into a gorgeous rooster who went back to the farm he came from as the only rooster with a harem of 22 hens.
So the point of this looong story is that if a hen is sitting on a clutch of eggs she will do all she can to hatch them all. As far as she is concerned they are all HER eggs.
Will these be your first chicks? It is an amazing experience.