Not sure whether it is just not allowed or whether its just a case of asking for the TOC workflow group to be added to the relevant MESH mailbox. If your ‘non secondary care’ provider has a MESH mailbox than try requesting the relevant TOC workgroup be added via email@example.com, I think that’s the correct address.
I know, for example, many GP Practices do not have the TOC workflow group on their mailboxes. Use this to check (HSCN connection):
If the workflow exits on the mailbox then you’ll see the organisation details in the body of the response, otherwise you’ll get something like this: