This formula in the "Also Notified" column works perfectly for one "Deputy" with one or more "Deputy Back-Up Contacts"
=JOIN(COLLECT({Deputy Back-Up Contacts Range 4}, {Deputy Back-Up Contacts Range 1}, Deputy@row), ", ")
However, when more than one Deputy is selected, the formula should return all the Back-Up Contacts for all Deputies selected. Instead it comes back blank. (for example, Aaron has four Deputy Back-Up Contacts and Gabby has one, so five emails should be listed.