First of all Allan, I assume you both have Zumo's, right? If so, this is how I have been doing it:
Create your route with Mapsource, then Transfer your route to your Zumo the normal way.
Once you have finished, disconnect your Zumo from the PC, the correct way as per the Zumo's manual.
Now restart your Zumo, it will recognise that there is new data and ask if you wish to import it, say yes. Once this is done you can now view your new routes in the "Where to?" menu, "routes".
select a route, you will now see that route with the various info of distance and time, with the choice of "GO" and there are some other options at the bottom of the page: Back, Map, Share, Edit.
Select "share". Now you will see a page with all your routes you have on your Zumo. You can either select separate routes or you can select all, your choice on which ones you want to share. Once selected, press the "Export" button . the routes are now exported to the SD card.
Now all you have to do is take the SD card out and place it in your brothers Zumo and Turn it on and you will be prompted to import the new data.
Its the same method for all your data on the Zumo, Waypoints, routes and pictures.
Job done, hope this helps.
