Mass upload of invoices by suppliers through Supplier Portal (alternative to FBDI)?

Hi everyone,

A customer is asking whether it's possible for suppliers to upload multiple invoices in batch mode through the Supplier Portal, without using the FBDI templates or a backend interface.

We are aware of the standard option to import invoices directly into Payables using FBDI templates, but the customer is looking for a more practical and automated approach that could be leveraged by suppliers themselves.

So far, we understand that invoices are typically entered manually by each supplier, one by one through the portal.

Is there any standard functionality or extensible solution (e.g., Excel add-in, Smart Forms, integrations) that would allow suppliers to submit multiple invoices at once directly from the portal, ideally with validations and ease of use?