pr link with contract

hi

my reqmt is like this

i have one service contract for supplying of computer papers. ok

but this info does not know all DEPTs in any industry.so what they will do is they will raise PR'S for comp papers of X & Y qty.

but procurement people know that we have contract for these what they will do is they will create release order agianst that contract

here there is no link between PR & contract

if i want to create link between so how can i do

i think u understand my reqmt

nani