I don't recall four Dunnunda forums but you may be correct.
I've been here since 1996 (only one original forum) and only recall three Dunnunda forums, but don't recall the name of the third forum.
PPRuNe policy is to reduce and consolidate forums where appropriate, rather than creating more forums.
I suspect Management are not exactly ardent supporters of Jetblast type forums.......
Feel free to contact Danny and/or PPRuNe Towers with your request.