i did not receive a seperate i797 approval for my Son


 I filed my dependents (wife and son) I539 back in 2012 June for H4 extension where my son was added to the I539  supplement. When i got the approval I received the i797 approval notice for my Wife but did not receive one seperately for my Son. Now when am due  for my second extension  Dec 31, my immigration folks are demanding for a separate i797 approval for my son also.  Now my question here is can my sons H4  extension be applied using my wife's i797 approval. Any thoughts on this would be highly appreciated


Note: am only filing for my sons H4 extension this time as my wife got transfered from H4 to H1b