R42800 - Sales Update - Assign Invoice No. - Final

Dear All
I Run R42800 - Sales Update - Assign Invoice No. - Final, with this will create Invoice Number and Sales Update.
in standard R42800 create Invoice base on (DOCO, DCTO, KCOO) from F4211.

IN My Case Invoice No. create base on (DOCO, DCTO, KCOO and SRP1). where I can set it,
Sample : in One Sales Order have 3 Items and  3 Different SRP1 , and  when I run R42800 - Sales Update - Assign Invoice No. - Final, it will create 3 Invoice

I Hope people here understand what I mean and can suggest me for solve it, Thanks

Regards

Juned