To generate a link that will allow anyone who follows it to join a discussion as a Writer, open the Discussion Menu and select ‘Discussion Settings’. Select the ‘Invites & Permissions’ tab. Under ‘Discussion Writer Invite Link’, click ‘Enable’. To disable the link, follow the same steps, this time clicking ‘Disable’. You must have Admin or Owner rights in order to enable/disable the link.
Note that this link should be shared carefully, as all users who follow the link will have Writer privileges. If a user has turned off the ability for other users to invite them to discussions using their email address (see: Turning off Email Invites), they will not be able to successfully follow a discussion invite link.
Alternatively, you can invite new participants directly to a discussion (see Inviting Participants to a Discussion).