Adding family member for the banking group

I have a premium banking with hdfc as a family group of 4 , is it possible to add the 5th member ?

My RM said we can have only 4 people in a group , and 5th as exception (which he said cannot be given to me as backend team did not approve) , not sure if he even tried .

Writing to premium group email just redirects to the RM and is not helpful

Has anyone else tried adding 5th member to group?