How to handle updating profile based on email and phone number

We have an integration with Klaviyo that will pass through standard customer fields like name, email, phone, etc and create a profile for them within Klaviyo.

If that same user then attempts to fill out one of our forms again in the future, we just update that existing contact record with whatever information they provided. Here is an example
 

John@gmail.com fills out one of our entry forms with:

Email: john@gmail.com
Name: John Doe
Phone: 111-111-1111
Zip code: 90210

In the future, he fills out one of our forms again, and we update the record with any new information:

Email: john@gmail.com
Name: John Doe
Phone: 111-111-1111
Zip code: 78704

However, now that more and more companies are just wanting to collect SMS/name instead of email, how do we handle a use case in Klaviyo where a phone number already exists on a contact profile and they submit new information? Should we just update the contact record as we previously had when they were submitting with an email? The only issue I can see with this is if two people in a household share a phone number (or even an email address)

Example:
Email: john@gmail.com
Name: John Doe
Phone: 111-111-1111
Zip code: 78704

Then John’s wife signs up through a form with just a phone number:

Example:
Name: Jane Doe
Phone: 111-111-1111
Zip code: 78704

Should we update John’s record with this information? Try to create a different profile with a different ID, or something else?