Hello JohnG3 ,
Unique email addresses and SMS phone numbers are what denotes unique contacts. Therefore, if multiple people are using the same email address, then you'd only realistically be able to have one of them as the primary contact for the First Name and Last Name fields. If you need to list other names with the contact, consider making a custom field for those additional names, and label them accordingly - i.e. child first name, parent/guardian first name, etc.
