How to make a DFF field visible or mandatory based on another DFF field value selection?

Summary

How to make a DFF field visible or mandatory based on another DFF field value selection?

Content

We have got the below requirement from business.

 

We require 2 fields (DFF)s under the 'Manage Position' screen namely 'Approved Start Date' and 'Approved End Date'. 

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Based on certain values (from value set - P1,P2,PP3,P4,P5) selected for 'Position Type' [Global segment DFF under 'Manage Position'] the above 2 fields should be available. For example, If Position Type == 'P1' OR 'P2' Then 'Approved Start Date' and 'Approved End Date' are VISIBLE. Or else if Position Type == 'P3', 'P4' or 'P5' Then 'Approved Start Date' and 'Approved End Date' are