" is it possible to edit the actual PowerPoint default templates for charts so she doesn't have to select the chart styles from the custom template section? i.e. she could select any chart style from the categories and it would automatically be in the correct colours, line weights, font, etc? is this possible or would I have to edit invisible files etc and know a bit of programming to do so?"

Thats exactly what I am trying to dins out, I hope someone can help!