Issue with Modifiers

Hi All,

We have one requirement actually Fuel surcharge modifier(Automatic) this is automatic modifier this should be calculated on manual Modifier discount.

Sales order unit selling price 199

Eg :Manual Modifier discount is 10

so 199-10=189

Fuel surcharge is 1 %

this surcharge should be applied on discount amount

189+1.89=190.89

please help me how can i achieve this.

Thank you,

Dinesh.