How do I add a family member to my iCloud storage

See the following Apple articles:

Set up Family Sharing

Set up Family Sharing - Apple Support

What is Family Sharing?

What is Family Sharing? - Apple Support

Make sure that each family member has a unique Apple ID

Make sure that each family member has a unique Apple ID - Apple Support

Add a family member to your subscriptions from Apple

Add a family member to your subscriptions from Apple – Apple Support (UK)

Share iCloud+ with your family

Share iCloud+ with your family - Apple Support