Yes, you can easily add bills and invoices that were paid outside of Melio and manually mark them as paid. That way they'll appear right beside your Melio-paid bills for safe and organized record keeping.
Just add the bill as you would any other (by clicking the purple + button on the dashboard's top left > Bill payment > enter bill details)
Then select the bill in the dashboard and on the right side click MARK AS PAID.
That's it, now it's marked as paid, and will appear like this:
As always, if you have any questions we're available at firstname.lastname@example.org