Time In Lieu
You can create pay items to track this in Saasu. From Settings > Payroll > Manage Pay Items, you can create new Entitlement and Wage and Salary pay items for accruing and taking this type of leave in lieu.
Note: You can open existing pay items and duplicate these to accelerate the setup process. This also helps ensure you use the correct W tax codes for these pay items (these will be used in PAYG reporting).