It will be hard to have anyone add until it is time to do an Update of their software.
You might want to email Garmin and ask to be included the next time they update.
Id research Garmin, TOMTOM, ect.... and find out what database they use, Im sure they share similar data, and who ever provides that data is who you want to talk to.
Weather or not this will take $$ is unknown.
For Topo Maps I use a 3rd Party download program called TOPO-Fusion which only shows streets, and topography, although you could manually add waypoints. Its neat cause it does 3-D which allows you to visualize your upcoming trip or past trip.
~Say hello to the rug's topography, It holds quite a lot of interest with your face down on it~
Looking for a place to put your photos try BackcountryAgenda