The initial submitter of an invoice has the ability to add additional comments in the "Expense detail/purpose" field. However, sometimes they don't put enough of an explanation. As their supervisor is approving the invoice, it would be great to allow them to add comments as well that the rest of the approvers in the approval flow can see. They would be able to add clarification to the original comments instead of having to return it for the submitter to edit/enhance their comments.