Restricting column edits without restricting visibility

I've been using SharePoint for a while now but this is my first foray into a slightly more complex project. I'm trying to create a helpdesk ticketing system which is split into 3 separate lists.

List 1 (initiator): This stores no data but is used to generate the form which the user will be able to fill in to create a new ticket. Information from the form is pushed to list 2 upon creation of an item and the item is then deleted (ensuring the list is kept empty at all times).

List 2 (admin console): This one stores the data for each ticket and is only visible to support agents. Changes to items on this list (eg status updates, changes in agent assigned) need to be visible in list 3.

List 3 (user console): And here is where I run into trouble. List 3 is supposed to be a place where users can go to check the status of their ticket. I want them to be able to find out who the ticket was assigned to, get updates on it etc. But I also want them to be able to add additional information to the ticket here using a comments field. As a result, I want all the columns to be visible but only 1 column (comments) to be editable.

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I've thought of a few ways around it but they're all a little messy. I could for example set up a workflow which is activated when an item in List 3 is edited. This would pull information from list 2 overwriting all columns except for comments. Effectively users would be unable to save changes if they make edits except to the comments column.

I've also googled around and found that using lookup columns may work, but I've been unable to get these working in list 3. When I try to point them to list 2, only a limited selection of lookup fields are available to me.

Any help on this would be massively appreciated.

• Emma