Start by checking legal SkyTeam routings. A lot could depend on whether VVO is considered Europe or Asia by DL. USA-LHR-AMS/CDG-EU is a pretty frequent legal routing on DL (and gets flat beds TATL), so you might try this to LHR/AMS/CDG and then continuing to VVO on SU, perhaps using someplace (St Petersburg?) other than Moscow to force the routing through Europe and to force SU and their routing rules. However, I'm not optimistic. You might also need to worry about the number of segments that are allowed, especially if DL doesn't fly SFO-LHR nonstop now.