Hi, I recently tracked my position walking in a park to try adding it to OSM. I’m using JOSM cause it performs better than a browser tool.
I downloaded the area and imported my GPX file. I converted it to data layer and simplify it to reduce number of points.
Now the path is perfect.
The new path is still on a separate data layer than the layer i downloaded from OSM.
Can i upload only this layer or do i have to merge it before?
Either way i get a warning message as i upload and i didn’t go further cause i fear deleting something i should not.
Thanks
Hi.
You can copy-paste between the layers. Make your GPX layer active, copy, make downloaded layer active, paste. You’d make sure, of course, there isn’t already a trail mapped there.
Alternately, and I think recommended, is to upload your raw GPX as a “GPS trace*”, then tick the box to include GPS traces when downloading data. This will show all GPS traces for the given trail(s), and over time the hopefully many traces will provide a better idea of the trail’s true path.
Happy mapping. 
(* On openstreetmap.org, or via built-in feature in certain apps like Locus.)