Thanks WalkonSunshine and Kelsie,
I will keep the calcium, as two of three have nice shells again. Don't if it was the extra calcium or just their gear started to work at last. They seem not to be worse for any extra calcium and I have always gave them a variety of healthy food since I got them, when they were 8 weeks old.
My daughter just had her after school chicken cuddle. They all come and want to have cuddle on her lap. They are spoiled chookies and we love them.
Watch for hard bumps on the eggshells. That's a classic sign of too much calcium.
I'm glad that they're laying more normally now.