We have a SharePoint site with lots of technical documentation. When new documentation is uploaded or current documentation is updated we create a new "News" object in a custom list. The news object can be of one of 4 different categories.
We would like our users to be able to subscribe to getting an e-mail notification for one or more of these categories when a new piece of News is published. I've managed to set up a workflow for automatically sending the e-mail to either a SharePoint group or a number of people in one field of a custom 'Subscriptions' list, but how do I let the users themselves add and remove themselves from the different categories? The user should just need to select/unselect a checkbox for each category.
I've currently got a custom list with the user and the four categories as yes/no fields. I thought I could get a workflow to add and remove the user as necessary from either the SharePoint group or the custom 'Subscriptions' list field, but I've so far been unsuccessful. I can't find any way in SharePoint Designer to add or remove from the SharePoint group, and I don't see how I can just add or remove one person from the list field. I've actually not been able to set the field at all (even to a single person) via workflow.
I've looked at Can I add a user to a SharePoint Group in a workflow but installing custom code will be a problem due to security constraints. How can I remove a single entry from a multiple People and Groups field via workflow? is similar to what I'd like to do.
Is there any way to do this without custom code? Or suggestions on how to get the same functionality another way? The site is in SharePoint 2013 Foundation but only the 2010 workflows are available.