Civil union in Portugal between an EU citizen and a non-EU citizen


My partner is in the process of getting her residence card as a third-country national who is a family member of a citizen of EU (me). We are in a civil partnership, so we’re required to show “documental evidence that they have been living in co-habitation for at least 2 years;” (taken from here).

The civil partnership was done in Argentina last year (in AR, the requirement is to have been living 2 years together to get it, so this should be enough to prove it). Nevertheless, I want to be sure she can get the residence card, so I’d like to do a “união de facto” here in PT in the Junta de Freguesia.

According to this document, it seems to be fairly straightforward to do it (statements under oath and birth certificates), although we went twice to the Junta de Freguesia and they think we can only do it if at least one of us is a Portuguese citizen.

As usual with the documentation, it is vague and confusing. Anyone knows for a fact if two non-Portuguese citizens can do the “união de facto”? One is an EU citizen, the other third-country national.