You can group related Bars together using the Container feature. A Container acts just like a Bar but can expand to allow for Bars to be grouped inside of it. They are great for representing a release or theme on your roadmap. Drag a new Container onto the roadmap, open the Container, and then drag new or existing Bars into it.
You right click on a Container to make a copy of it and all its contents. You can also right click and empty Container to convert it to a Bar.