The home dashboard of Moorr already estimates the tax paid for your entire household position, whereas the standard payslip and info from your employer do not account for the rest of the users’ income story outside of their jobs and other expense deductions.
As such, a tax refund/payable occurs whereby the balance actually withheld by the employer mismatches against the amount calculated (i.e. the amount shown within the ‘estimated tax paid’ on the home dashboard). As such, technically these tax refunds should never be treated as an additional income amount.
Regarding bulk income or once-off income, just add it as an “Other” type of income on the income page and select yearly.