Citizenship application for a child descendent of Australian citizen

Hi there,

We are applying for Australian citizenship for my 2-year-old daughter, whose mother is Australian. We are both together, and living in Canada, and her mother is labelled as the responsible parent. As I add the required documents to the application, it is “recommending” that we attached custody evidence. When I look at the details, the only thing that seems applicable is the following:

" A letter from each parent or legal guardian not included in the application, that gives permission for the child to be in Australia in your care. This letter should include a copy of the non-travelling parent or guardian’s personal particulars (biodata) page of their current passport.".

Does anyone know what exactly we need to attach? I assume there are specific requirements.

Thank you.