Steve I am afraid, this is not possible due to Apple Photos architecture. They have extensions API, and PhotoKit API, but none of that can be used to inject information about faces and people, only to read what Apple come up with.
As an idea, you can test alternative aproach. Tonfotos can write facial data into image metadata, and other photo apps, including Adobe, can read and use this information. However, I am not sure about Apple, internet has contradicting information about that. I think it would be great if someone would try that and report here the results for the benefit of community.