Originally Posted by
televisor
If you book a multi airline ticket from OTA that includes a non-LH group airline, you are guaranteed to get luggage included - the non-luggage fares just can't be combined with other airlines. (As mentioned before, I'm not sure what happens when it's only a mix of LH/LX/OS, but I have a feeling they'll be light since their fares can be combined).
I've had LX+OS+LH metal combined tickets which were Light fares. So definitely possible to stay "Light" as long as it's within LH Group.