Hi Jen thanks for posting in the Lucid Community! Lucid uses the email address you associate with your account as its unique identifier; unfortunately this means it's not possible to have multiple email addresses associated with a single account nor have one email address associated with multiple accounts.
I certainly understand how this ability would be useful for your workflow though and our development team would love to hear more about your use case via this feature request form. Ideas submitted here are passed along for review and are considered when prioritizing improvements to our products. Thanks for your feedback and apologies for any inconvenience this causes.