Multisite with two websites?

Hi there,

I currently run to websites:

https://www.highway.org.za and https://www.highwaysermons.com

Is it possible to multisite these two websites? They both have their own wordpress install. I would like to share the same ‘theme’ so when I can the theme on the one it changes on the other. They both have wordpress 3.4.1

https://www.highway.org.za is with a South African hosting company “Hetzner”
https://www.highwaysermons.com is with “Ix Webhosting”

Your help will be much appreciated.