The Patriot Yue Fei there are 3 emperors in Yue Fei's era; the oldest emperor (the father), the older emperor (the step older brother) and the recent emperor (the younger brother). Reason: The father heard that Jin's army was going to kill the Song emperor so he retired and let the crown prince reigned then the crown prince heard about the same gossip and said he's sick and let the younger brother took over.
And I dropped Si Jin, but if it followed the original plot, the reigned emperor (the father) will be retired while still alive and he'll let ML became the emperor but it should be very close to the ending. Reason: he wants to play with his pet and enjoy easy life.
