How many estab items by type ( unit, vehicle, weapon, ammo, formation ) are you talking about?
My question is really related to the French and Australian units i made for my Merdjayoun Scenario. You can see, in the attached screenshot, how many unique units i've made (though the Australians are shamelessly copied from COTA). The two french units open show most of the weapon types i've made. Each obviously has its own ammo. Most are simply renamed stock items (how different is an 8mm rifle round vs. a 7.95mm?) As for vehicles, i've only made one or two tanks. I've made no changes to the formation values.
So, its not an awful lot, to be honest, and it'd pretty rapidly recreate it all if I had too, but if i can't change the estab that the scenario uses then i'll have to scrap the whole thing and start that part again too!