If you add restrictions directly in the channel manager but they are not reflected in Mews, it’s because the connection works from Mews towards the channel manager and not the other way around.
Restrictions set up in the channel manager are not sent back to Mews, and therefore Mews always overrides them whenever a new update is sent to the channel manager.
The best solution is to always manage the restrictions directly from Mews so that your sales are synchronized. However, if you prefer to manage your restrictions directly in the channel manager, you can disable the updates from Mews to prevent them from being reopened. Can I manage restrictions directly in the Channel manager?