I use the "Person Shown" field in Bridge. Bridge interprets this field different than other software which is creating issues for me. Names are separated by semicolons which Bridge interprets as line breaks. Other programs write the metadata as one line separated by semicolons.
Person A; Person B; Person C
<rdf:li>Person A; Person B; Person C</rdf:li>
the workaround is to put the names in quotes in Bridge "Person A; Person B; Person C" but this is a laborious task to go through on every image so that it is compatible with all of the software that requires semicolons.
Work on test images/dupes, once you are happy you could add additional arguments to overwrite the original files, or to only process specific file formats or to ignore specific subfolders under the top-level target folder etc.