In cases where companies want to give an employee days off for one-time events like Weddings, the best way to support this will be:
1. Create a policy with 0 allowance.
2. Minimum balance of 0 (so the employee can't get into a negative balance).
3. Max balance of the amount he is entitled to (So he can not exceed this amount in case they forget to unassign him)
Then the next steps will be:
1. Assign the employee to the policy.
2. Add manually the days you want to give the employee.
3. Unassign the employee with a future date after the one-time event.
The reason we do it this way is that policies update each cycle (Annually or Monthly) so by setting the policy to 0 days and adding the days manually, we overcome this issue.