Beneficiary Import Should Not Allow adding person if he does not exist in Employee'd Dependents

Beneficiary Import Currently allows adding any random record as Child Beneficiary. This goes with MemberID and MembertypeID as NULL.
Where as through UI, only Employee's existing dependents are Populated in drop down and adding another person is not possible.
Import should restrict adding random record as dependent beneficiary.

THIS TICKET is created to sync the code with UI refresh branch. old UI JIRA is WT-4675