How to propagate a new option to a column on several site collections? (choice or metadata)

Question

I'm trying to accomplish the following scenario :

• I have a content type named MyContentType
• It contains a column named MyColumn.
• MyContentType is hosted on a content types syndication hub ( /sites/hub )
• several other sites (/sites/a, /sites/b, /sites/c...) have subscribed to it through the Managed Metadata Service

Now here is what I'm trying to achieve : I want MyColumn to offer a choice of values to the end-user, either by being a Choice column or a Managed Metadata column (whatever works).

I'm facing issues in both cases:

- Option 1 : When I make MyColumn a Choice column, then the first publication propagates the choices fine, but later on if I add a choice to that column on the CT hub, then the choice does not appear on the subscriber sites. Even If I check "republish" and run the two required jobs ("Content Type Hub" and "Content Type Subscriber")

- Option 2 : In order to make MyColumn a Managed Metadata column, I proceed as follows :

• I created a /sites/shared site collection where I create a local term store containing the terms that will be used as values by MyColumn. I do not want to create that term store at Web App level, but strictly at site collection level (I have thousands of SharePoint sites to manage and I don't want to create term stores all over the place).
• I've added the URLs of /sites/hub, /sites/a, /sites/b... to the "site collections access" field of the term store group of /sites/Shared, so that they can all access the values
• But then when I try to publish the column, SharePoint shows me a message telling me that its values are stored on a site collection to which not all subscribers have access (SP therefore refuses to publish).

I feel like I'm in a dead end. What's the correct practice to propagate choice values to several site collections, but let me change them in only one location?

Answer 1

Since you are using the content type hub to distribute the content type I think it only makes sense to use the term store at the tenant /web app level. That approach seems to bypass this issue. Do you have a test setup where you can verify this?

Answer 2

Since you know the sites this change should apply to you could update the site column in each site using powershell. Is that an acceptable approach?

Answer 3

Kasper suggested that the solution would be to add a Term Set group at web app level. Indeed it's the practical solution, but before I mark his answer as the correct one, I want to explain why SharePoint does not offer a real solution to this use case :

• the managed metadata values are stored at site collection level or web app level. I have n sites that need to share those values but I also have 2,000 other sites that should not know these values. Therefore I chose to host the data of my n sites onto an n+1th site, and I've shared its term store group to the n sites.

• The CT hub is stored at "service" level. I mean that you may define exactly one CT hub per managed metadata Service. No more. When you try to publish the CTs (containing metadata columns), SharePoint does not check to which sites you have opened the term set group that these columns feed on. Therefore it simply refuses to publish the CT.

That's a pity. Both features should work with the same scope, or at least SharePoint should check the access permissions of the site collections.