I am planning to upgrade to version 3.0.3 from 3.0.2. I have made some changes in the web pages in 3.0.2 to change some of the default language that is presented to users. For example, I have modified the wording presented to customers in CustomerTicketOverView.dtl to soften up the words.

When I upgrade to 3.0.3 these altered files will likely be stepped on and thus the wording will have to be modified each time an upgrade occurs. Has anyone come up with a simple way to manage this?
I have created a summary maintenance Word document that keeps track of the changes I made so I can redo them if needed, but I was wondering how others handle this? What files will NOT get overwritten by an upgrade?
I first thought that the Package Manager might provide updates but it appears that a full install is needed to upgrade an existing system. Is that the case?
Thanks so much.