Hi @anon62427974, welcome to the Asana Community Forum and thanks for taking the time to share your feedback with us! As it stands, it’s currently not possible to create sub-teams. The current Asana structure allows you to create an Organization, teams, projects, tasks and subtasks:
We don’t have plans to update this structure at the moment and create subteams but I will share your feedback with our product team so it can be considered in the future. We also have a popular threads where you can upvote for this feature: Project Folders (sub-teams).
I hope this helps!