attach proof of payment/ bank remittance to paid invoices

attach proof of payment/ bank remittance to paid invoices

I would really really like to be able to attach the supporting documents that an invoice has been paid to the invoice record.

How to do that?

I mean, I can attach docs to this forum

Attachments
Desktop Zoho Docs Google Docs

but NOT to the invoice/ expensing tool I'm paying for? What gives?