https://caltopo.com/m/7N7B In this example, if I split Hall Ranch outside loop at the point indicated,
then try to attach it to Oops!, sometimes the lines will join at the other
point of intersection, in this case the point where I've indicated the
trailhead. Does that make sense?
While I guess this question still stands, I've since realized perhaps a better way to do this is split the line at a point, delete the part I don't want, then extend the original line vs drawing a second line and trying to join them.