STO use schedule agreement

Dear my friends,

I have a problem  about STO business ,in sand system ，the STO   order is a PO  ，and the salse condition type PB00 &PBXX could reach from PO ,

the copycontrol from delivery to billing  use condition source as 'A'  (from po)  ,this is no problem.

but now ,we use STO  order is not a PO, it's a LP (purchase schedule agreement) ,the salse condition type PB00&PBXX can't copy from LP, is there any way to deal with this problem?