Help Editing A Campaign

I’m currently trying to figure out how to edit/mod one of the premade campaigns that already exists in the game- specifically the Battle of Bapheus historical battle. I need pointers/assistance in creating several modifications to it that would allow me to do the following;

1.) I want to be able to play as the Byzantines rather than the default Turks that Osman leads.

2.) I would like to rewrite the victory conditions to where the Byzantines now must face the various Anatolian Beyliks who unite together against them, essentially making it a 3v1.

3.) I would also like to edit the Catalan Company’s behavior where they will try to aid the Byzantines against the various Turkish factions around the map.

If anyone is willing or able to assist me in this, I’d be extremely grateful and will even offer compensation for help in generating this as a custom scenario.