Question:

Is it possible to set up an Email Fragment so that it is only made available for one or a set of Email Templates?

Answer:

This can be achieved with fields on the Email Template / Approved Document (instead of being controlled at the Fragment level). Please see this linked Vault documentation

If the user does not have FLS access to the below fields on the Approved Document object in CRM, the default behavior is to display all email fragments for the associated product.

• Allowed_Document_IDs_vod
• Vault_Document_ID_vod (Document ID)
• Allow_Any_Product_Fragment_vod

Related Documentation:

Vault Help Documentation: Setting up Approved Emails