I'm still getting the hang of nested templates so I'm probably doing it wrong and if so, can someone tell me the right way.

My goal is to have one master template which holds the main nav bars for the site. Then I'm making all kinds of nested templates from the main one and those contain various links on the left side depending on which department the nested template belongs to.

So here's what I've been doing.
I have the main template for the entire site. I choose to make a new page from that template, click on Nested Templates and name the new one PR. Then, from the four editable regions all ready there (header, banner, leftnav, and main) I create new editable regions from three of the four (header2, banner2, main2). Now those regions have blue names under their yellow names. The leftnav region I'm leaving untouched because I'm adding the links there particular to that department and they may be subject to change.

Now, when I update the main template, it automatically updates all the nested templates. That works fine. My problem is, if I update the links in the leftnav region in the nested PR template, it doesn't update all the pages based upon that template. Also, I thought the leftnav region was supposed to be locked and the only regions that could be edited were the yellow ones I designated when I made the nested template. However, I've had one of my content managers change the font size of the leftnav region (which she's not supposed to be able to do) and also this region doesn't update when I make changes to the links in the PR template.

Am I going about it the wrong way? I want the leftnav region on the nested template to be locked. If I open the main template, make my changes and do a save-as to a new name, then I'm thinking if I change the main template, it won't be reflected on the other one, and that's not what I want.

I await your feedback.

I may look like I'm doing nothing but at the cellular level I'm really quite busy.