You can submit an application to the Regional Directorate Education of your last school of attendance for a certificate of six years/nine years at a Greek school in Greece for the acquisition of Greek citizenship as long as you are:

• the interested adult or authorised person 
• the guardian of the person concerned for the acquisition Greek citizenship or authorised person

You will need to:

• fill in your personal Taxisnet codes
• fill in your personal details, email address, schools
• attach the required supporting documents (photocopies of the passport, birth certificate and certificates of study)