Need and additional sidebar in Vantage Pro theme

Critical: My questrion is below, but when I tried to activate your WPMU DEV Dashboard, it broke my multisite network. wp-admin still seems to be working for arre/division site, but is just a white screen. Please resond ASAP and I will give you log in rights somehow.

I have a multisite installation with several subdomains (12 areas, 88 divisions). In the beginning, my client only wanted a single sidebar on left. I did a lot of research and decided on the Vantage Pro theme. It is a well built theme, but and I (my PHP partner) have extensively custimized the theme to accomodate extreme complex client needs. So going to a new theme is more then a challenge.

My client now wants two sidebars. In child theme, we were able to register an additional side bar, add a sidebar.php, but are not certain:

1. Where to add php code (and proper coding) - i.e. child; page.php, single.php, etc.

2. What child style.css is needed.

Can you assist? Is it possible to add an additional sidbar on the Vantage theme?