Notifications on emails with multiple recipients

We use Nylas to read our users’ mailboxes, automate some actions in our platform and show the email thread through one of our apps. We can focus on the email thread part to simplify things.

Our use case is to cover emails sent to many of our users and resolve all those to a single conversation. For example, an email to Foo with Bar in cc should create a single conversation

We rely on the object property grant_id to identify the receiver of the notification, which works well, even when bcc’ing, for a single recipient. The problem comes when having multiple recipients because we get different notifications, which would trigger the creation of separate conversations - we can’t seem to find a way to group them.

We tried using the to, cc and bcc fields, but it didn’t seem reliable because bcc would come empty. Also, when emails were sent to a group (e.g: group@example.com which redirects emails to Foo and Bar) we couldn’t identify our participants through those fields without mapping them to that group.

Is there something we’re missing from the docs? Or are we using Nylas incorrectly to our use case?