Getting recurring contributions with Authorize.net that predate CiviCRM instance to register in CiviCRM
This would be incredibly difficult to do, because you would need to create recurring contribution records with the correct IDs matching those that Authorize.net is sending.

In this situation, I usually use the Offline Recurring extension.  Please download from the link above; the original authors no longer maintain the extension, and this branch on my copy is the only version with no known bugs.

Create offline recurring contribution subscriptions to match those that exist outside of Civi.  The missing contributions will be added to CiviCRM, but it's up to an end user to manually mark failed payments.