Originally Posted by jdrtravel

I think for award tickets Delta's logic is working like this:

1. There are no companion upgrades on award tickets.
2. Medallions (all medallions) have an exception to this rule as a benefit of loyalty.
3. Non medallions never get this exception, even when they are a companion to a medallion.
4. When the exception is applied, companion upgrades work the same way as they do for cash tickets: highest level medallion drives priority, award tickets taking the lowest priority among eligible fare classes for Delta customers, but above sky team and other eligible non-Sky Miles groups.