Multisite Set-Up & Configuration

I purchased Support Plugin and noticed after purchase that it only works in multisite set-up. I have multi-sites .... just not multisite configured !

I have as my main site and I have as an existing sub-domain. Both operating on their own wordpress configurations.

I actually want to run the Support plugin on the training.reachcms url.

Is it possible to merge these two sites into a single multisite configuration so I can run the Support plugin ?