Until an unlicensed user accepts an invitation, it is not possible to edit their First Name or Last Name, or their Email Address for that matter. When adding a new unlicensed user either individually or via a bulk upload, Smartsheet stores their email addresses in a central location (most likely for future marketing purposes!). If a data entry or spelling error is made in any of these three key data fields, we can't fix it quickly because Smartsheet returns the original name associated with that email address – very frustrating!
Furthermore, quite often many 'fake' email addresses are used for Resource Management or demonstration purposes (and apparently piling up in a database somewhere) – and because their invitations to join will never be accepted, we cannot re-use them within the same account with a different name. There is only so much that can be done using aliases to 'live' email address.