Possible to combine GMapTool USA maps?

I've been experimenting with OSM maps and Basecamp. Results were good but not ideal.

I purchased the downloadable version of Garmin's City Navigator North America maps and am awaiting delivery.

In the interim I downloaded (with some difficulty) the routable topo maps from the GMapTool site. (Only the USA Northeast and South Atlantic maps for my possible trip planning). I installed them quite easily and they seem to work well.

However I am wondering if I can combine the two regions into one so that I don't have to switch between them. I can't seem to loctae how it might be done on the internet.

Thanks for any advice.

Jeff