AU Payroll - Edit posted pay runs
You should be able to edit any payrun that hasn't been 'filed' regardless if it was the last one or not. I enter several unscheduled payruns and I've noticed an error in one but I can't fix it because it wasn't the last payrun posted. The "work-around" Xero recommends is to File it and then re-post a counter fix. This feels redundant and unnessary extra work. Essentially its saying I can post an inverse of the original to cancel it out which isn't a tidy way of doing work.

Hi Jamie, just coming back across your idea here. In Xero Payroll as of right now if you've a posted pay run that you need to make adjustments to, you can revert this to draft and make the required changes.
The only time we wouldn't recommend doing this is if the pay run's been filed with the ATO.
Once it's been filed we'd recommend using unscheduled pay runs to make any changes. This is because reverting a filed pay run to draft will cause issues in the reporting to the ATO.