Your customers can now use the same email for multiple accounts. You will need to assist your customers in setting this up. You will need to send them an invitation from each profile to their email if they wish to have the same login for every account.
What will it look like for a customer who has used the same email for multiple accounts -
After entering email and password, they will be prompted to select which account they are accessing.
Once the customer is logged into their account, they will have the option to toggle between accounts without having to log out. Select the initials in the upper right hand corner and select the account to access from the drop down.