You can issue your civil partnership certificate.

You will need your personal Taxisnet passwords.

According to those performed in Greece

If your cohabitation agreement was performed in Greece and has been registered with the competent registry office, you can issue:

• immediately online the extract of your most recent cohabitation agreement
• through KEP / Municipality / Special Registry Office the full deed of your most recent agreement. In this case, your deed will be issued at a later date, and you can also request deeds of your older agreements.

Agreements concluded abroad

If your cohabitation agreement was concluded abroad and has been registered with the Special Registry Office of Athens, you can issue:

• immediately online the extract of your most recent cohabitation agreement, provided that it was drawn up on or after 22.01.2018. 
• through KEP / Municipality / Special Registry Office, extracts or full deeds of all civil partnerships you have entered into abroad.  In this case, your deed will be issued at a later date.

In any case, the response to your request will be posted in your gov.gr inbox and will bear the security features of gov.gr.