The LH booking engine is only showing these due to BRS-BRU SN operated flights.
That's true, but the published fare between BRS and NRT on LH clearly shows that BRS-BM-FRA is allowed on the fare component.
Code:
/BETWEEN AREAS 2 AND 3 VIA SIBERIA WITH NONSTOP BETWEEN EUROPE
AND JAPAN OR KOREA/
1. BRS-BM/LH-DUS/FRA/HAJ/HAM/MUC/NUE/STR-LH/OS/SN-BRU/DUS/
FRA/MUC/VIE/ZRH-LH/NH/OS/SN-NGO/OSA/TYO-LH/LX/NH/OS-TYO
2. BRS-BM/LH-DUS/FRA/HAJ/HAM/MUC/NUE/STR-LH/OS/SN-BRU/DUS/
FRA/MUC/VIE/ZRH-LH/NH/OS/SN-TYO
3. BRS-BM/LH/SN-BRU/VIE-LH/OS/SN-DUS/FRA/MUC/ZRH-LH/NH/OS/SN-
NGO/OSA/TYO-LH/LX/NH/OS-TYO
4. BRS-BM/LH/SN-BRU/VIE-LH/OS/SN-DUS/FRA/MUC/ZRH-LH/NH/OS/SN-
TYO
You can see from this that there are routings that are impossible, but I'm pretty darn near certain the only change between this routing list and the original 2008-2009 one is references to BD have become BM.