How to connect two leave type


I would like to know if it is possible to connect two leave types in ERP next.

We have vacation leave for 30 days. Employees take unapproved and approved leave.

Approved and unapproved leave should be subtracted from the 30-day vacation leave allowance.

If an employee applied for approved leave, it should be subtracted from the vacation leave.

You cannot merge them, but in your situation, you can add one leave type and use it to apply in both situations and add a custom field that indicates if this leave is an Approved or unapproved leave type

can u please elaborate this