vim ftw. (there is an incorrect solution at link) :)

  Gddggdd
  :g/creditcard\":null/d   # to get rid of null credit cards :)
  gg
  qa
  9x
  f"
  d/creditcard
  c2f"
  ,
  ^[
  f"d$
  j^q

After that, just <num>@a and set.

edit: fix format and add gg after null deletion.