if you have migrating aircraft, means you have multiple exes
if you want stand alones, take each exe and assign it the theater you want (naval, Europe, Israel, Balkans etc)
then go in and delete the birds you dont want. feel free to add in birds that you do want from here or other sites
same for terrains. althought the delete process here is to have a copy of that terrain folder and a blank terrain ini
if you make an install that is not a stock TW one, you will need to leave one stock bird in minimum. This is for ones like ODS 30AE or my Balkans install that im working on building up for post Cold War era
takes a little work, but its quite feasible