PRs with addition of only line items and Clubbing Service and Normal POs

Hi SAP Gurus

We are in ECC 6.0

in our buisness process The PRs are created by the Project system

they could create only one PR with the Same No Repeating all the time and when ever a new PR is created it is adding up to the existing PRs line items where the line item has increased to 800+ nos now,

also they are clubbing PRs of service and material PRs. we need it to be separate

as service PRs and Mtrl PRs are processed separately by different Dept and cannot use the same PR which is here only One at the same time.

only the line items are getting added eventhough the PR is released,

i have created 2 Document types for PRs with Different No ranges, pls let me know how to assign this Document type to Project system PRs creation so that different PRs are created for Both Material PRs and ServicePRs.

Pls tell me how the Above problem could be Solved.

Thanks and Regards

SATHISH