It might be an interesting mini mod to change the date a few years, but even then it would be really difficult. No way it's just a few strokes of the keyboard in ds.txt. Get the family members' ages changed first. Possibly remove some characters who haven't been born yet, and add some who haven't died yet. Change the province ownership where needed - some scripts have to reflect those changes also. Change the army placement where needed. Change diplomatic relationships where needed. Change any scripted disasters to reflect the change. Change all the year in history traits (the dating text at the front of each) to reflect the change. Break up the KH faction, since pushing it earlier back makes it too distant to really think of it as an alliance of any sort. Etc.