Updating the derived factor in an absence plan

Summary

What is the best way to update the derived factor in an absence plan

Content

We need to update our absence plan with a new derived factor for length of service and are planning on using the 'Alternative Seniority Date' and pull the Legal Employer Seniority Date as the accrual calculation date. With that said, we are uncertain if we can Replace the current derived factor in the absence plan with the new derived factor, or if it would be better to create a new absence plan. Any advice is greatly appreciated.

Version

We are on 19B