This is very simple to change. Xij scales the bond order term between I-J pairs, and the bond order term further scales the attraction term with the leading coefficient Bij. Since Xij is a scaler and a simple constant, you can just combine it with Bij by making the Bij between I-J pairs = original Bij * Xij. Isn’t this simple?
I believe this was what was done for the newer SiC parameters – the Bij in the parameter file included the effect of Xij.