To relise this ,you need to change the purchase condition record.
Terminate the validity date of YFR3 of vendor 998 and 995 and activate
YFR1 of vendor 998 and 995 via MEK2 and also its price value to 3.8%.If you are not familar with the maintainance of purchase condition record MEK*,you can ask someone who is an expert like TH0RK(YFR3 creater).