Garmin Legend CX question

I would like to load maps for the entire Missouri River on my Legend CX. I have to load from two cds, Western US and Eastern US. The problem is when you switch from one cd and load from the other it erases everything from the first. There is plenty of memory and I would rather not buy a second memory card. Any suggestions?

Did you call Garmin?

not yet
I hate getting put on hold so I thought I would try here first.

Go to their web site and ask
After I purchased second (or third? Maybe fourth!) Garmin product, I had trouble with the software and used their web site for help. An excellent (clear and to the point) reply came back rather quickly. Problem solved!