Converting back for a campaign

[SaS TrooP]

OK, here is the situation:
I created a SPWW2 long campaign as Italians, starting June 1940. At the battle 1 deployment phase, I saved the game and converted it to a single player scenario for my friend to deploy they units for me. I played the scenario, finished it, and here is my problem: I seem not be able to convert it back to a campaign, so my core force gathers experience and I have another theatre selection options.

How do I solve that?