Sorry to hear that. It would be easier to stop if it was vitamin related.
Hope your GCM pullets start laying soon. I have not seen the egg color yet from my birds offspring. Liz sent a PM to say her OE pullet from my Ameraucana x GCMs just laid her first egg. I am anxiously awaiting a picture of it. It will be the first of my OE chicks to lay.
We'll see about the BCM... :/ Really don't want to have to get rid of her.
I can't wait for all your chicks to lay either! Want to see how dark the GCM eggs are and can't wait for the olive eggs. If you get a pic will you post it? Ahhh! Hopefully only another month or so for the OE and the GCMs look like it'll happen in the next couple weeks.