The rule for who can share a document to other users is: any user who has edit access can

To test this:

- Share a document to another (specific) user, with edit access

- Log in as that user

- That user can share the document with other users in turn

However, they should then be able to remove the access they've given to any additional users. The display of the share sheet supports this: in the attached screenshot, I'm logged in as dominics-test, and I've given access to dominic-test-101

However, even though the X beside dominic-test-101 is enabled, when I click it as dominics-test (i.e. a non-owner edit user), I get a lost connection error

(This is caused by Firestore refusing the delete to the roles)