Hi @Rimedur.
Welcome to the Sonos community and thanks for bringing this to our attention. This is not yet a supported setup. Sonos’ home theater set up is up to 5.2 1 surrounmd sound set up, having the availability to add 2nd Sub on your Sonos Home theater setup. The setup you are trying to configure is 7.2.1. As per other members of the community, using the group and ungroup feature as a temporary alternative way of adding additional speakers to the home theater set up has delays and this has already been confirmed by our engineers.
However, What I can do is I would be more than happy to send this to our engineering team as a feature request. I would like to suggest subscribing to this thread and to our announcement topic for any feature releases, bug fixes, and feature updates. Just to set your expectation, you will not be contacted by our engineering team for updates or any information related to this feature request. So I highly suggest subscribing to our announcement topic and to this thread.
Please let us know if you still have any feature requests or feedback by creating a topic. We would highly appreciate it. Please do not hesitate to share more feature requests or feedback so we can help each other out.
Thanks,