Transfer book from my iPad to a family member

Set up Family Sharing. Otherwise you don't.

Family Sharing - Apple

This is how. Not only for the iPhone or iPod touch.

That's partially correct. They must be using Family Sharing - Unless the family members share the same Apple ID. If they don't (which they shouldn't), they need to use Family Sharing.

Aah ok. Sharing the same Apple ID is not very handy. I’m wondering why some people are doing this.

Is the problem solved with mine and rbrylawski information?