On the subject of Mo-jiao's four princes:
Banchabana was Yu Xiao
Budala was Shangguan XiaoXian
Duoerjia was Lu Di
After thinking about it for a couple of years, hehe... it is very likely that Die-er-bu was the original Mo JiuXing (or Mo WuXing), the original leader of white-clothed kamikaze troops in chapter 1. He would have gotten killed by Shangguan XiaoXian (SXX) a bit later.
SXX mentioned that she only feared Mo JiuXing, Han Zhen and Yang Tian. Han Zhen and Yang Tian were both killed afterwards (they were suspected to be Bu-da-la or Gufeng instead of SXX).
So that leaves very little candidates who are powerful enough to be Die-er-bu. We know that SXX is smart enough and ruthless enough to lure the original Mo JiuXing, trapped him and killed him. Then she took Die-er-bu's jade and showed it later to Ye Kai when she posed as Mo JiuXing (in chapter 27).
If the original Mo JiuXing was SXX, she would not have sent Mo Bai to die uselessly trying to get the dolt SXX. So the original Mo JiuXing was alive and well in chapter 1 (or 6) but got killed before SXX showed up as Mo JiuXing.
Sorry, I know this is an old subject, but this thing sometimes percolates very, very slowly. And who knows what Gu Long was originally thinking, but this looks like a plausible explanation that could wrap up the story nicely.