I do enjoy attempts to try to increase the historical accuracy of A&A, and I’d be willing to accept a bit more complexity in order to get there…but my feeling is that there just isn’t enough support for the ICBA / ISR split in A&A Global.
Historically, the reason why Italy’s government split in two is that the Allied campaign bogged down in central Italy, so the Allies wound up occupying southern Italy while the Axis occupied northern Italy, in a stable way, for a long period of time. The reason that happened is that Italy has highly mountainous terrain, and to a certain extent the Americans were (in my opinion) using Italy as a training campaign, as a diversion, and as a phony war – the goal was less to conquer Milan as quickly as possible, and more to get some real combat experience for American troops and to “prove” to the Soviets that the Allies had opened up a second front. The Italian offensive tied down a few German divisions and forced Germany to redeploy reserves that might otherwise have tipped the balance at, e.g., the Battle of Kursk – but, again, the point of the Italian campaign was to tie those divisions down, not to occupy the industrial cities of Milan, Venice, Turin, and Florence.
None of this can be easily simulated in A&A Global. There is no such thing as mountainous terrain, you don’t have to worry about what the Soviets will think about the Allies in a post-war diplomatic environment, and there’s no ‘rail movement’ or ‘strategic movement’ phase that could be used to redeploy German forces from Smolensk to Northern Italy in a reasonable period of time.
Worse, by the time the Allies are occupying Southern Italy, the Italian economy is likely much too small to bother splitting. Like, realistically, what is the maximum extent of the ISR’s economy? Southern France, Northern Italy, Yugoslavia, Albania, and Bulgaria are worth 11 IPCs, assuming you get lucky rolls and keep all of your territories. You’ll also be lucky to hold onto all of that as the Axis for more than one turn after Rome falls – you might see Northern Italy trade hands the very next turn, and if you don’t, you’re likely to lose Marseilles and/or some of the Balkans. Same problem with the ICBA economy – you’re looking at a maximum of about 10 IPCs, with a more likely average of 6 IPCs. It’s just not worth the bookkeeping of maintaining a whole separate economy (and another turn in the turn order) so that you can dump a couple of infantry onto the board for a couple of turns.
Finally, denying Rome to the Americans as a place to deploy new recruits is sort of unrealistic in that southern Italy was very much a staging ground for the Allies. If you follow the principles behind the ICBA/ISR split, you should probably also have some kind of rules for “free Scandinavia” and “free Holland” and so on. The ultimate result is to say that America can never have its own factory in Europe, because all potential factory sites are occupied by the respective liberated powers. That’s going to throw off game balance something fierce.
I think the idea of a split Italy makes a lot more sense in the context of a theater map that focuses on the Mediterranean, or, at most, on Europe, North Africa, and the Middle East. The Global map is just too large to support a special focus on the details of the Italian government.