Add flex field on Development Goal Screen

Summary:

We want to add a custom field on development goal screen. But, Looks like both Performance and Development goal screens share same flex field HRG_GOALs.

Content (required):

I believe it can be achieved by adding field on HRG_GOALS descriptive flex field. But, HRG_GOALS descriptive flex field is shared by both Performance and development goal screens. If I add one field, It will be visible on both screens but i only want it to be visible on development page.

I can enable/disable the fields via personalization(Page Composer) but i need to do this on all pages(Create, View, Edit etc). I just want to know if this is right approach or there is another way of adding custom field on development goal page.