Difficulty: HardFabricate claims to conquer all the independent counties in Italy. If your Realm Priest has poor Learning you can restart at the beginning, because it saves you much time. You don't need to control all of Italy so when you have enough land you can form the Kingdom of Italy. This is step 1/3. For the second one, you need 1000 Piety and 500 Gold. You get the Piety by doing 2 pilgrimages and the Gold automatically. For 3/3 you need 50 dynasty members. You have to marry your children and their children and if it is a girl always use a matrilineal marriage. If it is possible for you, you can convert to an faith like Adamitsm to get more wives.
Credit to
Bayek von Kuwaq on Steam for his
guide.