Can I make my Gridalicious child theme work with Gridalicious Pro?

I have just bought, downloaded and installed Gridalicious Pro. Up to now I have been using the free version of Gridalicious with a child theme for my customizations. My question is, can I make my existing child theme work with Gridalicious Pro, or do I have to start over and make a new child theme? To ask the same question in a different way: Is Gridalicious Pro treated as a completely new theme or as an upgrade from the free version? My site URL is https://operasandcycling.com/