Living under one roof as individuals requires a lot more information to be provided to Centrelink so they can accurately assess whether you are indeed a couple or a single.
To this end you will probably be required to complete the Centrelink Relationship Details Form. The ex-partner living in the same house will usually also be required to complete the form as well.
You can include the completed forms with your application or wait for Centrelink to ask you to do it.
We can share this form with you or you can download it from the https://www.servicesaustralia.gov.au/individuals/forms/centrelink website.
Our friendly team here at Retirement Essentials are more than happy to help, simply call us on 1300 527 727 during office hours.