When you sign up for Vaultastic, a default LegacyFlo login for the postmaster@<Vaultastic Domain Name> is created. This id is used by the automation to fire LegacyFlo requests to move data from Active to Open store, etc.
You can also use this id to login to the LegacyFlo interface to view the status of requests submitted and to submit new requests.
Since, you can see only the requests submitted by the logged in user ID, having multiple IDs may make it difficult to monitor overall status.
However, the system allows you have multiple login ids. For more ids, contact Mithi Customer Care.