Like imagine playing as Bormann's germany and you could simply place missiles in Trujillo's Dominican Republic aiming at the US, triggering an international crisis.
So here's a brief tutorial on how to maximize the Italian economic sphere going on all potential countries that can join it and how to get them
Bosnia:Tito and his partisans take over Yugoslavia, let the bosnians revolt and then invade Yugoslavia
Serbia:You can only get them if you democratize and the partisans under Cosic win
Bulgaria:Boris has to flee during the Macedonian war, the fatherland front takes over and negotiate with Macedonia, once the negotiations are succesful let the paternalists or socialists win the elections and declare a Republic
France:Sidos has to be leader, fall into civil war and then Sauges shall reunify the country
Algeria: Win the Algerian war
Syria:win the Italo Turkish war and push for Scorza's deal
IEA: when the horn collapses inmediately invade and reconquer everything (only if you are Fascist, whether be Democratic or Scorza)
Iberia:Win the Iberian wars and try to get 100% of influence over both Portugal and Spain (Otherwise Germany might take one of them into their sphere instead)
Morocco:get both Portugal and Spain into your sphere
Cabo verde and Gambia:once you win in Portugal there's a chance that they'll join back as a colony and get into your sphere (the West African War must keep going or the winner might invade Gambia before they can join you)
Chad: Already in your sphere, but You can get them bigger if the WEU collapses and they win against them in war
Venezuela and Guyana: Venezuela should first join Iberia (preferably with Perez Jimenez), when they collapse they'll join your sphere if You are fascist (otherwise they'll join Germany)
Colombia: Win as New Granada and let the Italophiles or Diego Garcés Giraldo win the power struggle(i prefer Giraldo since he has better economic bonuses for Colombia). If the Brazilian civil war triggers Colombia can annex a small portion of the Brazilian amazonas
Gran Colombia:let the fascist win in both Colombia and Venezuela and they'll form the Gran Colombia
Ecuador: let Velasco return, he'll join the Iberian sphere and then the Italian Sphere once Iberia collapses
Panama: Arias Madrid shall win and when Iberia collapses they'll join your sphere. You can also get them the Panama canal during the Oil Crisis if the US backs off
Costa Rica: Calderón gets in power and a Socialist revolution triggers off, a fascist counter revolution will take over and then join the italosphere
Honduras:Military Junta takes power, they lose the football war and after a nationalist coup, Honduras will align with Italy
Dominican Republic and Haití: Trujillo wins, that's it.