If you would like a member to add other members to the website, you must make them an administrator.
To allow a parent to edit their spouse or children, set the parent's role to "Regular Member +(Edit Spouse/Child)". An administrator must assign the relationships by assigning the spouse and the children in the member's profile. Afterwards, the member can then edit their spouse and children.
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How do I allow members to edit their spouse or children? - 
