Many egg crafts call for a blown egg. This is an egg shell that you have removed the egg from without breaking the shell. This isn’t hard but does take a little patience. You can still use the eggs in baking or scrambled eggs.
In this video an 11 year old demonstrates the technique.
Whether you are having the girls blow the eggs or preparing them yourself for a craft, I’d recommend allowing at least 1.5 eggs per girl with the assumption that some will get broken along the way.