who ultimately submits the completed questionnaire to my customer's portal

You submit it yourself, always

Supplia does not submit anything to your customer's portal. The system recognizes the questions in the list you upload, fills in the answers from your chain file, and presents them to you per answer with a yes/no confirmation. After that confirmation you receive a completed list back, which you upload or enter yourself in your customer's portal. We never log in to a third-party portal and have no access to it either — this is a deliberate boundary, not a technical limitation that still needs to be resolved.

That also means: if an answer changes — for example because the number of employees has been amended since the last update of the file, or because a new location has been added to the countries where the undertaking is active — you check that yourself before you submit. Supplia does not flag any changes to your customer; the file is maintained on the source side, and the confirmation step per answer is the moment when you verify that.

Why this is how it should work

This follows from the division of roles set out in the platform introduction: Supplia builds the answer side of the chain, not the submission side. There is no integration with customer portals — not with those of banks for the VSME basic module, not with a NIS2 portal for the ten measures of Article 21(2), and not with a portal where ISO/IEC 27001 Annex A is assessed. The reason is that Supplia does not declare, certify or assess anything: no quality judgment is attached to an answer, only a match between question and file. Submitting is an action you perform on behalf of your own business, with your own login credentials at your customer's portal — that remains with you, even if the answers themselves are largely generated automatically.