How do we add a custom Error Message for Minimum 1 attachment for single DOR type and not all

We tried doing it via Manage Messages and modifying the error message for Minimum One Attachment Document of Record, but then the change reflects to all other Document Type - Document of Records as well.

We can't use AutoComplete Rules due to some limitations, but still if there is a sure shot way please drop it, and we will try to accommodate it.

We also can't use validations on DFF as we want this error message on system given field of attachment.