SAF-T localisation for portugal

Hi all,

I am working for a software house integrating our software with Dynamics NAV for a client in Portugal. We were asked to implement a certified SAF-T (Standard Audit File for Tax) solution for signing our invoices. We asked first our NAV partner in Portugal, if it can be done in NAV. But he stated that there is no standard solution in the localised Portugal version and that it is by default not SAF-T certified.

As I worked before in Dynamics I am a bit puzzled as NAV usually addresses the local regulations within the localised version or with a partner solution.
Does anybody know a SAF-T vertical module for Portugal or a partner that already implemented it? I tried to search on the internet but couldn't find anything specific for Portugal.

All help is much appreciated. Thanks!