Adding to OpenSteet maps

I have my local home map area installed on my Edge520 utilizing OpenSteet Maps. I will be travelling out of my home area coverage by OpenStreet maps. I would like to add OpenStreet map coverage of my travel destination area. Can I just drag that new OpenStreet map file into the Garmin folder I have already created called gmapbmap which contains my home area maps or do I have to delete the home area maps first. I have storage space for additional maps. Any advice would be appreciated.

Simplest thing to do is to copy your existing local map form the 520 to a PC hard drive and then just add the new away map following the same steps you did to put your local map on the 520 initially. When you get back home simply delete the away map and replace with your original local map form your PC hard drive. DC Rainmaker's instructions can be found at http://www.dcrainmaker.com/2013/05/download-garmin-705800810.html to cover the whole creation and uploading of OSM maps to the Edge 520.