Is my restore process being badly affected by this third-party non copy-only backup?

This question may read like a duplicate, but is situation-based, and is posted from confusion applying the knowledge from other answers. I've read dozens of articles (among 1 , 2 , 3 , 4 ), but am finding conflicting opinions (based on my understanding, which is now suffering from information overload, or perhaps not including enough information in my other questions). I am creating this question therefore to get a definitive answer based on my situation. Given the following backup scenario, I need to know **whether the third-party backup software would prevent me from performing a full recovery to the point of the latest backup (18:00)?** Time | Action | Device ------|----------------------------------------------|---------------------------- 12:00 | Full backup (non copy_only) | D:\MyBackupDevice 13:00 | Tran log backup (non copy_only) | D:\MyBackupDevice 14:00 | Tran log backup (non copy_only) | D:\MyBackupDevice 15:00 | Tran log backup (non copy_only) | D:\MyBackupDevice 16:00 | Full backup (non copy_only) VSS snapshot | Third-party off-site device 17:00 | Tran log backup (non copy_only) | D:\MyBackupDevice 18:00 | Tran log backup (non copy_only) | D:\MyBackupDevice 19:00 | Disaster strikes | My restore goal is to restore to the point of the 18:00 backup (I know there is a tail-log backup that can be added in as well to get the remaining transactions up until the disaster, but let's keep things simple for now). Based on this answer , I believe that the third-party backup causes a conflict with my own transaction log restoration (as per this answer ), which prevents me from performing my restore to that point. My understanding is that the transaction log backup contains data since the last full non copy_only backup. Is this correct? Does the third-party backup prevent my own restore routine from working because it is a non copy_only backup?