Populate Single Select with Lookup


Hello dear Community

As the title suggests, I am trying to populate a Single Select field type with the results of a Lookup. Is this possible?

I looks like I’m not allowed to paste links here so I cannot share my base, so I will describe what I want to do below.

I have a table of persons, and a table of emails. A person can have more than one email. So far so good.

I then have a third table called service that lists all the persons that belong to some digital service (think JIRA). Obviously you can only have one email address per account on such a service. So I want a field that presents me with a dropdown of emails associated with the person in that record.

First prize would be for me to be able to update the service table with a new record, lookup the correct person (add if it does not exist) and then if I add an email that is not already associated with that person just update person.

Second prize would be for me to update person first with the email, and then go to service and add the new record into service looking up the correct email.

Is this not possible?