Help! Is it possible? and If so, how?

G’day guys. I was wondering if it were possible after adding new Faces to a textured project, whether I could somehow add those new Verts/faces to a UV Map so that I may texture the new Verts without ruining my old texture and UV Map?

Some times what I do is move my map off to the side so i can work on parts of the mesh separate. Select old map and move off to the side select new and unwrap then edit in uv image editor. then you need to merge verts on the UV map if you want.