External guests and Teams SharePoint site - unusual access question

Hi RB_MMII

See here

https://microsoft365pro.co.uk/2019/07/14/teams-real-simple-with-pictures-controlling-who-can-edit-documents-in-a-channel/

You should be able to do it by amending the permissions on the underlying sharepoint site and giving the specific guest owner or edit permissions and everybody else view or limited view permissions but as you say, it would break inheritance.

The other way I can think of doing this is to set up a completely seperate SharePoint site with no Team attached, set the permissions as needed (the guest owner or edit permissions and all others view or limited view) and then sufacing another document library inside the channel (using a document library tab). Having tested you can do this in both public and private channels. Doing it in this way may be advantageous so you don't break the inheritance of the sharepoint site that the Team sits on

Let me know how it goes and hope one of these ways answers your questions

Best, Chris