Hi chara
Welcome to the Forum
Not really sure what you are asking: A 'portfolio' is simply a collection of things - usually documents - but a 'Property Portfolio' is a generic description of a collection of properties.
Not sure where you think this may be 'registered' - your proprietorship of a specific property is registered with the Office of Titles in your state or territory, and with any rateable authority such as the local municipality, water board, and land tax office.
Other than that, you have to keep your own records for tax purposes .... that's about it!
Does this answer the question?
Cheers
Kristine