Initial ticket booked as SIN - FRA - IST is issued by *A partner on an Award booking. I'm not actually worried that there will be any issues from that partner if I miss one leg.

Ticket for FRA - VIE is issued by yet a different *A partner for that LH flight.

I'm not sure if SQ will care if I don't intend to fly the FRA - IST sector (when they are not the issuing airline)? If it will be an issue then I'll just tag it to FRA and collect and re check it when I'm there.

But I'm just wondering if others have been in this scenario and if so whether it's any problem if I check it to VIE.