What type of documents are requested by Case Officer (CO) for relationship proof ?

What are some factors affecting the visa processing time ? → What are some reasons for Permanent Residency (PR) visa application rejection ? → Who can be a sponsor for 491 Family Sponsored visa ? → What is the minimum income threshold for a 491/191 visa ? → How to mirror a visa application into your IMMI account? → What type of documents are requested by Case Officer (CO) for relationship proof ? → What does my visa status mean ? → Do Department of Home Affairs and Australian Taxation Office share data for visa applicants with each other ? → What is condition 8579 and can I continue to live overseas on my 491 visa ? → What evidence of employment can be requested in a S56 request for a 189, 190 and 491 skilled visa ? → How to see the expected visa grant date for your 189, 190 or 491 visa application? → Is my occupation on visa processing priority list? → How is the visa processing time estimated on SmartVisaGuide? → What is 8515 visa condition? → My visa is delayed and I am lodging a complaint. Can you share some tips and tricks? → What does an Assessment Commencement Letter look like? → What is Commencement email and Request for Further Information (RFI)? → How does DHA calculate visa processing time? →