How can I give access to invoices on the Parent portal to a non-resident parent?

If a Non-Resident Parent needs access to their child's invoices via the Parent Portal, turn on the Receives Invoices flag on the Related People Tab on a Person Record. This flag is reserved for situations where the family shares an Invoice.  Custody alone will not prompt these to display for them automatically, their permission needs to be granted. 

Please note that a Resident parent does not need the 'Receives Invoices' flag designated because since they are a resident parent their access is automatic.