How to disable Open Missing Reference Model Pop-up

Creo 2.0- When I open a local copy of an old assembly, there are missing merged parts that cause a warning "Reference model ### is not in session.  Please select it." along with a pop-up window to select the missing .prt.  I am using the assembly for analysis only and don't need the base parts so I end up selecting Cancel on a whole bunch of these base parts.  Is there a way to disable this pop-up?

Thanks,

Matt