Seat Selection when flying different airline
I've booked a flight with LH, but with part of the ticket being on South African Airlines. Both airlines are slopping shoulders on the seat booking and saying I need to reserve seats with the other carrier for the long haul section from MUC - JNB. I suspect not, but is there any way to get a seat reservation before 24hours? I wouldn't mind too much (other than my usual OCD about getting the best seat), however I'm flying with my partner. We had to make a separate booking as I wanted to get a more expensive ticket so that I get *A gold (T vs L). It would obviously be great to sit next to her on the long flight. Or failign this is there anyway to merge the tickets?
On another note, not that it matters for this trip, but If I book a ticket through LH in T class do I get points from an LH ticket or points from the airline I fly? For this flight it's ok as Asiana gives T 50% on SAA and LH. But if this differs what do you get?