I wanted it to work like this:

tabs for 'article' node type:
'edit': edit the article node type
'manage fields' manage fields on article node type
'manage display' manage display for article node type
'comment fields' parent tab for when article node type has one or more comment fields
--'comment field 1' parent tab
----'manage fields' manage fields for comment field 1
----'manage display' manage display for comment field 1
--'comment field 2' parent tab
----'manage fields' manage fields for comment field 2
----'manage display' manage display for comment field 2