Post election edit FF for DOB and gender check

Currently we have post election edit FF to check DOB and gender of dependents who are enrolled in medical, dental and vision.

We need to display error when employee tries to add any dependent who do not have dob and gender. If we use the logic to check DOB and gender in contacts, system will through error when we evaluate a life event.

Here , system should allow to evaluate life event even when DOB or gender is missing, however should through an error when they try to add the dependent without DOB and error.

Could anyone suggest the possible way to achieve this.