Need help setting up new groups

[Tsunami]

I'm trying to create new groups that allow users to open reports from different packages while only being able to build ad hoc reports off of a single package withing Query Studio.

For example, I have created a new group that is supposed to use one package for reporting and a corresponding portal with copies of reports based off other packages.  The problem I'm running into is that the users can use their package for thier ad hoc reports, but they cannot run the pre made reports within the portal.  I recieve an error saying that they do not have access for those packages from which the reports were written.  I have granted "Execute/Transverse" permissions on the packages but it doesn't seem to be enough.  However, if I grant "Read/Execute/Traverse" the reports will run but the users will have access to those packages within Query Studio (which I don't want).

Any suggestions?