I want to share iOS apps with my daughter.
I have macOS 10.13.1 on my MacBook Pro.
In "System Preferences" I have selected "Share my purchases with family" in "Purchase Sharing" "My Apps & Services" but when I go to "Manage Family" (I am the organiser) the "+" button is greyed out and I cannot select it.
I actually have 2 accounts; the initial Apple ID, which I use for all purchases, and a second which I created for Contacts and Calendar etc to share across my Apple devices. The second is shown as family member for sharing.