Automatically Notify Ticket Contacts

Good morning,

I'd like to find out if there's any way to have a ticket automatically add its Contact(s) (i.e. anyone in the People tab) when adding a Comment without using a global setting, or to pull a Contact into a workflow's Notification step. I don't believe these are possible based on some testing and searching, but I might be missing something. I know there's an "Add Group" button when using the Update action on a ticket that might be the end result, but I'm looking at the Comment field and Notification workflow step for now. 

I know that there is a global setting to, "Notify all by default on ticket updates," but that's a bit too far for what we're looking for. If there's a similar setting similar to that global one that a technician could enable within an individual ticket, that would probably be the ideal. Alternatively, if there's a way to enable something like that on a particular service or form, that might work as well.

Another option I thought of was to use a workflow's Notification step, but it doesn't appear that there's an option of "Contact" (or anything similar) in a Notification step's "Recipient's Role(s)" field - which is where I'd expect it'd be listed if it existed. I have a feeling this doesn't exist because the Contact(s) on a ticket could be fairly dynamic (i.e. there could be none, or there could be 100 Contacts).

Barring any of those possibilities, the only other option I can think of is to create a custom attribute on a form, and have the technician enter a person or email address into that attribute when working the ticket. Then pull that custom attribute into the workflow's notification step. The concern there is, if the custom attribute contains a manually-typed email address (i.e. one that's NOT associated with a "User" record in TDX), I'm not sure if the Notification step could process that (I'll test more). 

Any input is appreciated.

Thank you.

Nate