The option to bulk import users from one group to another is not available on our platform. For now, custom work is needed to achieve this feature. But I do agree that would be a really good feature to have. You can share this great idea on our new roadmap. Head over to https://www.buddyboss.com/roadmap and click the + Submit idea button to suggest a new feature.
I just want to set your expectation that we haven't run any extensive tests yet on this plugin but feel free to give it a try.