Does Shopify Multipass upsert the customer record?

Question

Shopify Plus has a feature called Multipass -- https://shopify.dev/docs/admin-api/rest/reference/plus/multipass

Multipass login is for store owners who have a separate website and a Shopify store. It redirects users from the website to the Shopify store and seamlessly logs them in with the same email address they used to sign up for the original website. If no account with that email address exists yet, one is created. There is no need to synchronize any customer databases.

Consider the scenario that a user performs two multipass logins where the user's last name is passed as an optional field, but prior to the second login attempt, the user changes their last name. Does the second multipass login, which passes the new last name, result in an update to the Shopify customer record?

Answer 1

Further down the same page, it states that

Shopify uses email addresses as unique identifiers for customers of a shop. When registering customers in Shopify, the merchant must set the unique identifier in the "identifier" field in the following cases:

The site uses other identifiers (such as usernames) Two different users of the site might be registered with the same email address If the email address is always unique, setting the "identifier" field isn't required.

Only one Shopify account can use a specific email address. Registering a second customer with the same email address (even with a different "identifier") will result in an error.

This means that user is identified using unique identifier, that may be email or something else if specified. So in above scenario, if the email is same and only last_name or any other attribute is changed, a new user will not be created but the information will be applied to existing user identified using that email.

Answer 2

I think it is pretty simple. The first time you access Shopify from Multipass, a customer record is created with the information provided. Nothing else can happen until that customer reads the email sent to them, and has them confirm their account. Whatever the customer record is at this time, is then confirmed and considered their record. So the second login, assuming it happens AFTER they confirmed, would be moot. If they tried logging in BEFORE confirming, Shopify would likely throw that attempt out, as the non-confirmed record exists, regardless of the last name change.