As a minor, I have no legal documents utilising my given name other than my birth certificate, my mother's healthcare and education records. I would like to add a middle name to my name. I have the orthodox first name, middle name and last name, of which I would like to keep all with the addition of simply using the new name as a middle name as well. Is it illegal to utilise both names in legal documents and registration in the future, e.g. when I register a card or medical issues, etc. or is it legal to use it all?