How can we add Flex Field to the MANAGE SALARY screen?

Summary

How can we add Flex Field to the MANAGE SALARY screen?

Content

Hello,

Is there an option to add FLEX FIELD to the MANAGE SALARY screen?
I checked the flexfields of salary and added to them but didnt see any field added.
( I checked - CMP_SALARY_BASES, CMP_SALARY_COMPONENTS ,CMP_SALARY)

Please see screehshot attached of the required screen that we would like to have the new flex field.

Thanks ,
Revital