After composing this question, I had some time for clarity and figured out the simple answer. It was certainly one of those palm to the forehead moments.
However, may it will be useful for other newbies (like me).
Is there a limitation regarding a value list returning a calculated field value?
If not...any suggestions as to what I should change to display the contact first and last name?
The answer: In the calculated field - ensure the calculation returns as Text (not a number).
table Company is related to CompanyContacts.
table Company is related to CompanySites.
table occurrence CompanyContacts2 is related to CompanySites via field "companyID".
The Value List:
In a table "CompanySites", I created a field called "Supervisor" that uses a dynamic value list.
The value list uses values from CompanyContacts::_pkContactID and shows values from the second field CompanyContacts::_ContactLastName. Values only include related values from the T.O. CompanyContacts2.
This works fine in a pop-up on the field Supervisor.
When it does not work:
If, instead of using the second field value CompanyContacts::_ContactLastName, I use the results of a calculated field CompanyContacts::_ContactFirstLastName (this is a calculated text field
"ContactFirstName &" "&ContactLastName") the value returned is the contactID number.