I can get it to work with anything less than party of 4 custom characters. I think it's registering party of 4 custom characters as full party so when I meet SH, it's already considered full party.
You are right ... I have read coments there and they say that 3 is top this mod allows you.
In the words of the senior NCO instructor at cadet battalion: “If you ain’t cheating you ain’t trying. And if you got caught you didn’t try hard enough!”