Hello Steve & Welcome to Just Answer,
Sorry to hear of any issue you may be having in doing this project.
May I ask if you have ANYONE in the organization that is familiar with these devices AND some of the more "advanced" features (such as the ones you described - adding "points of interest" - POIs)?
OR - do you have someone in the group that has at least USED a Garmin Nuvi in the past, and understand what "favorites" are?
One other question about the water sources: Can you give me an APPROXIMATE count of those sources?
I know these may be unfamiliar terms to you, so that is why I'm asking.