Hi ParichehrAfzali-3078,
This request has been declined by the feature team.
However, you can continue to up vote this topic in this new link:
https://microsoftteams.uservoice.com/forums/555103-public/suggestions/39466306-nested-teams-and-sub-channels-re-opened.
Microsoft will always focus on customer’s feedback and experience. Some new features would be added to the services based on customers' feedback in the future, and your good ideas will be very helpful for them to improve the service.
Your time, understanding and cooperation will be highly appreciated.