One way of being able to access a marker in Leaflet after being created. The example is from upcoming project, and includes several uses for accessing marker IDs. Leaflet-Geosearch was used to convert addresses to latitude and longitude. Repository credited here:
https://github.com/smeijer/leaflet-geosearch.git
The "locations" in reference is data queried from a database, passed through a Flask route to an html file, then captured and JSONified in a JavaScript variable.