So I sketched something, exited sketch mode, sketched another something...and darn it, now I have two sketches on the same plane and if I want to "extrude" them I need to do it separately. How can I UNITE the two sketches so they will be one sketch WITHOUT changing their locations on the plane?

The copy-paste method appears to change the location of the sketch.

Attach is a simple model I've made to demonstrate the problem. Sketch 2 and Sketch 3 are the sketches that need to be united/merged.