I've can now confirm that this is possible as I expected. In the case of the nuvi 40 with 'one-off' lower 49 OEM and subsequently purchased LM for entire NA, i dl'ed the NA gmap folder to PC and sent the full NA to the 4 GB microSD inserted in the unit together with the gma code as one gmapsupp containing the unit applicable unl.
The old 2014.10 map and associated files remained on the unit memory and had to be deleted manually. The new files such as JCV are of course not offered with this method, but using the other method [outlined in the preceding post] of directly dl'ing the lower 49 and then separately loading a second image from the gmap folder of the missing balance of entire NA only gets the reduced size JVC applicable to the OEM maps with the direct dl in any case.
Bookmarks