Why are my parents unable to view their invoices on the Portals?

If parents are unable to view invoices on their portal, it is likely because they do not have the "Receives Invoices" checkbox checked on on the Related People tab of their person record for each of their children that they are expecting to see invoices for. Make sure that the 'Receive Invoices' checkboxes are selected on the 'Related People' tab of the parent for each of the applicable children.