Rethinking Performance Appraisals: How to Handle Changing Roles and New Evaluation Methods?

I have been asked to change the performance appraisal form that is currently used in the company. Currently, in the appraisal form, employees are asked to mention their 5 KPIs and assign weights to them. Subsequently, the Head of Department (HOD) will provide his weightage. However, the management feels that a new method needs to be introduced. Another issue is if a person's profile changes twice during the evaluation period, which profile should be evaluated.

Please let me know if you need further assistance with this matter.