Swapping hardboiled eggs for fertile eggs?

[PouleChick]

I am one of those who always uses flock raiser with oyster shell on the side and never switch.

I think that is what I'm going to do from bits I've read on here - I'm really happy with how happy and healthy my flock looks and I think I'll probably have quite a mixed flock ages wise at least through the summer with my 2 broody hens!

Wondering what the controversy is about marking fertile eggs?

It isn't about marking them - it is about using Sharpies - I'd read that some people are concerned about the toxins going in to the shell. I've moved the other silkie out so normally we should have no extra eggs but I did find Doris had managed to get in there the other day so I quite urgently need to check on the eggs and get rid of it if she did manage to lay.