Nope, you will have to speak with Steam to try and recover the platform account. If Steam doesn't help, then you won't be able to modify your cross-save setup, as you have to authenticate all accounts. [quote]Destiny Player Support and Bungie cannot modify or remove accounts linked to Bungie.net profiles. To protect player privacy and data, you must be able to log in to any linked accounts to prove ownership prior to modifying your linked account. If you no longer have access to a linked account, you will need to reach out to the specific platform’s support for assistance with account recovery options. https://help.bungie.net/hc/en-us/articles/360049498031-Destiny-2-Cross-Save-Guide[/quote]