Love the F-5/F-20 family but I'm stuffed if I can think where to put them in my alt (over the top) ADF.
I have the RAAF going US (RAAF Reserves going Swedish), the Marines following the USN/USMC, the RAN going UK/Aust/US (and maybe a dash of French) and the Army going French. No room for Northrop except maybe advanced trainers and dissimilar air combat training.
Maybe I need a fifth arm, a Customs and Excise / Coast Guard or a Gendarmerie, that could eventually have its own air arm, including fighter / light attack aircraft? Maybe the Australian Gendarmerie (or a more appropriate Anglicised name) could be Australia's primary HADR and Peace Keeping organisation but has its own easy to support air power, including F-5A/B, replaced by F-5E/F and then by F-20A/B. Just a couple of squadrons, never more than about 50 airframes in service, but used throughout the world from the late 60s onwards supporting UN interventions where first line forces weren't required.