Reports & Discoverer :: Creating A Report Sever For Each App?

At the moment we have 10 apps using forms and about 6 of them using reports. All the reports get run from the forms. We are upgrading forms and reports from 10g to 11g and the dev teams are not willing to recode the forms to pick up ENVID's etc. i have 1 reports server running and have configured to run one of the apps reports but my question is how do i get the other apps to run under that report server, can this be done.I have thought about creating a report sever for each app but not sure if this is best practice and a bit over kill.Would i be wrong to create a report server for each app.