It's been established that Murong Bo and Murong Fu want to restore Yan dynasty.
What exactly did they want? Certainly it was more than the emperor's head. Otherwise, it should be relatively easy for Murong Bo to sneak up and kill the emperor, given his unstoppable martial arts talent. They would need a lot of support from the central plains in order to control the large population. But did they have any support, after all their effort? Did they also want to restore the dynasty, with their own people in the government?
It just seems like they weren't accomplishing anything.