The SkyTeam timetable also shows a routing via SVO with Aeroflot. This involves an 8hr (afternoon) layover in SVO on the outbound, but is actually somewhat quicker than KE on the inbound.

However, SVO-ULN and vv is only on SU-metal three times a week (there is also a twice weekly SU codeshare on OM-metal, but I'd guess that is not eligible for award redemptions).

However, I don't know the specifics of what DL would or would not allow as a routing.