Regarding lines on DynMap
After uhhhhhhhhhhhh over a month of thinking, I've came up with a solution for the modifying line segments problem:
Use different lines for each segment between 2 stations.
e.g: NV to RA is 1 segment, RA to RM is 1 segment, ..., RV to OP is 1 segment.
Then, put all of those into 1 single set (not Stations set like what y'all are doing).
e.g: Line 1 set, Line 2 set, etc.
So when you want to modify just a small segment of a line, it wouldn't be necessary to modify the whole line.
Now if anyone wonders: "But you can't name different lines with the same name!". I'll test it out and send it on a later post.
^^