As you grow and accustom yourself to using our product for your portal, there would be some changes made at your end to alter group composition and move agents according to their field of expertise. When you are looking at combining groups, what I could suggest is have one parent group called "Support" or "primary service" with all the agents in the smaller groups that you want to merge together. This is because even though you cannot merge groups, you have the functionality to associate the agents to multiple groups. 

In order to add a new group, please navigate to Admin -> Groups -> kindly click on "new group" to facilitate this.