EL expression to mandate flexfield based on a value in another flexfield

Hi,

We have a requirement to mandate 3-4 flexfields based on the value we give in another flexfield.

Business Scenario:

Flexfield 1: Do you have tech certification ? (response will be yes/no)

If Yes, Flexfield 2, Flexfield 3 and Flexfield 4 should be made as required field.

If No, Flexfield 2, Flexfield 3 and Flexfield 4 should be made as optional field.

Please let us know if anyone have any EL expression to achieve this requirement.

Any help is much appreciated.

Thanks,

Drisya G Kumar