Civi 5.15.1, WordPress 5.4.1
Some of our contacts ask us to send our communications to someone else, a "designated contact" or DC. To accommodate them, we created custom Contact Reference fields for email and phone/text, and for mail we use Civi's built-in "Use another contact's address" feature. To mark someone as a DC, we created a Contact Subtype and a Smart Group based on that subtype. However, new DCs don't come around that often, so our back-end data entry staff haven't consistently remembered to use the subtype. Also, we wouldn't otherwise need the subtype because there are no custom contact fields associated with it. We just need the Smart Group.
So I was hoping to get rid of the unnecessary subtype step, and modify the Smart Group to be comprised of contacts who are the selected values for either of our custom Contact Reference fields or Civi's surrogate address field. I've looked at Advance Search, Search Builder, and the Custom Searches, to no avail. Is such a thing possible? Thanks.