Please go to the Articles under the Member's section on "Separate a Member into their own Family". There articles there that cover making a current member of a family into their own family (like for an adult child no longer living at home or in case of a divorce/separation). There is also an article on adding members from a family into this new family (when a bride joins the grooms family, or a child moves from one parent's home to another parent's home).
https://gbdioc-parish.freshdesk.com/a/solutions/articles/44002211226