Hello Cathy

To be honest I'm not sure if the expansion will work.
The Extra Pack 1 was made to work with the C-130 X-periance base pack.  The DVD version is a mix of several models from all the packs.  
I couldn't say how an installation of the Extra pack over the DVD install would work.  It may corrupt things like the anti piracy component of the expansion and mess up all your C-130's.

Sorry I can't be more help.

Dave