Hens often do quit laying eggs while they are molting. But I have had a few that continued to lay eggs while molting, and apparently OP has some that do it too.
Most people worry about protein during molting, but weak shells are a good reason to be concerned about calcium.
Another possibility: most bags of oyster shell have powder at the bottom. You could add some of that to the wet mash, as a way of forcing the hens to take in more calcium.
The bone...