Each incremental backup is linked to the last full backup that was performed before the incremental backup. As a result, each full backup is linked to all incremental backups that were performed between that full backup and the next full backup.
You can restore a service instance from an incremental backup without the need to restore the full backup to which the incremental backup is linked. In this situation, you are responsible for ensuring that the service instance is in a consistent state after the service instance is restored. See Restoring an Oracle SOA Cloud Service Instance from a Backup.
However, you cannot delete or archive a full backup to which one or more incremental backups are linked. If you want to delete or archive a full backup to which incremental backups are linked, you must delete or archive the linked backups first. See Delete a Backup.