For email we use email address as contact key. For push we use UUID as contact key. And in contact Builder it appears as separate records and we can identify them as same customers. Yes I know that we need to use consistent contact key across channels but this is how it was set up unfortunately.
My question is, if we replace email_address as contact key for Mobile push instead of UUID would the contact appear as single record in ‘Contact Builder’ after this change?
Also how can we update these changes in the app in order to change contact key to email-address? If we just replace existing UUID to email-address in the code, will this update the contacts that already were created in marketing cloud (contacts that has UUID as contact key)?
Is it going to apply this change only to the contacts that got in after the code change?
Please let me know how we should go about this change?