I hope you and your hens get over loosing Leonard soon.
I thought that if a hen lays eggs, she is fertile. If none of the eggs develop with a committed broody or a good incubator it’s the roosters ‘incapability’ when the eggs wont start to develop. Maybe you are right and there is more to it , like a flaw in genetics why the embryo doesn’t start to develop in the egg.
With only 2 eggs there is no guarantee at all for a future rooster. But I understand you don’t want any chance of getting more than 2 cockerels.
Can you give an explanation of this sentence? I was guessing you mean herding the flock but otherwise I don’t understand what you mean by saying this.