Attached Link: http://www.sciformz.com

Well, ok, I am not the expert on mesh control. But what I can say is this: Simply adding a face or even a segment to an existing shape does not necessarily mean you are altering the construction of the shape UNLESS that program constitutes it. The "added edges" are simply another object I believe. They are not one in the same. For example, in my program, there is a tool to "Add segment" to an existing object. That then becomes part of that object respectively. The key thing to remember is that there are many ways of doing things in a modeling program to achieve the same results. Find a method that is easiest for you to accomplish what you want or one that you feel comfortable with. Gees, I hope I explained myself well enough. Sorry if I confused you more. :)