Thanks for your informative and swift response. I was asking to see if I had missed some other reason as to why it would be better to map it the way you had. It great to have confirmation.

I forgive you and accept your appology ;)

Now I'll tell you about what I presume to be a fairly unknown feature in the ID editor, to make mapping similar features with simple areas that share nodes much more convenient. The two buttons you need to know are F and backspace. This works with lines and areas. 

Say we were to re-map the residential areas here using parts of the forest geometry. Select area (3) and click on a node you want to be shared by the residential area and forest, then click another in the direction you want to travel along the existing area. Now press or hold F to add shared nodes and use backspace to remove them. You can also click to add (non shared) nodes freely and follow multiple existing lines or areas. No need for splitting or messing around with relations. I hope this helps and is easier than the methods you are currently using. For a full list of ID shortcuts press "?" They aren't all discussed in the help section, so you may want to experiment and see what's possible.