Upload the Contact SSN,Marital Status,Gender via HDL after the basic details have been uploaded long

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We have uploaded the Contact data long ago, now during the Benefits enrollment,we realised that the Contact SSN,Marital Status,Gender of the contacts also need to be captured for third party integrations. 

How can we update the details via HDL? Could you please let us know how can we use the HDL Format? Shall we use the Person number of the Contacts?