CloudM Migrate supports multi-domain migrations. This means you can migrate primary and secondary domain users from the source G Suite instance into primary or secondary domain users in the destination.
You can now specify full primary SMTP email addresses in your ‘User/Resources’ page in the Export Name and/or Import Name fields
Next, on your ‘General Migration Settings’ on page 4, you can specify domain and (if required) address replacements.
See https://support.cloudm.co/hc/en-us/articles/360008400360-Domain-Address-Replacements for more information.
Be aware that attempting check users or migration and then changing any Import Name consumes a license for each unique Import Name. Please visit the How is CloudM Migrate licensed? How are licenses consumed? article for more information on how licenses are consumed.