Single Transaction for Subscription and Sale

[RayOnTheGC]

I often have users who will make a purchase along with a subscription.  Using the REST APIs is it possible to combine this in a single transaction?

This site appears to do what I want to do but a cursory read of the of the APIs didn't give me any clues as to how it can be done.

[RayOnTheGC]

The original post didn't include the URL for the site that appears to have resolved this issue, it was www.jtsstrength.com/

Is there no one who knows how to do this?