Australia separated parents: do parenting arrangements and child support have to be decided together?

No. Parenting arrangements and child support are related but separate issues. Services Australia says separated parents can choose self-managed child support or apply for a child support assessment, while parenting arrangements can be agreed privately or dealt with separately if agreement is not possible. Official sources: Services Australia and Federal Circuit and Family Court of Australia. Guide: https://getinstantlaw.com/family-separation-divorce/what-to-do-first