http://scn.sap.com/docs/DOC-33203
Hello
For one SO line item (Say supply of material) , you can create only one order i.e. Network in PS.
However , you can create multiple WBS (Materials & services) and assign WBS to std. network.
CN02 - total tab , Assign different WBS to different activities.
You can refer above document for SD-PS integration.
Regards
Shubham