Project Packages

The project I am working on is being delivered in multiple packages. Sheets in the TI package need to have identical numbers as numbers already used in the issued shell package. As you are aware, Revit will not allow this.

I have separated the two packages in the project browser by assigning unique sheet volume parameters and organizing the sheets in the Project Browser by volume. I am currently using a suffix in the sheet number parameter (in the case of the TI package I am using the "-TI" designation). We would like to eliminate this suffix and relocate the "TI" designation to the "Project Number" parameter separate from the "Sheet Number".

Does anyone have any suggestions other than assigning the TI sheets unique sheet numbers different than the shell sheet numbers already issued?