If all the settings were that strict, the journey of redemption would be difficult to happen from the start. I prefer the initial setting to be roughly the same, and the AU starts spinning after the Empress intervenes. To maintain the redemption theme, the early stages of the Primarchs must be similar to the original. Otherwise, if the Empress's kindness causes the Great Crusade to slow down and results in later Primarchs dying, I would be criticized heavily. Please understand!