Both Gerlinde Kaltenbrunner and Maxut Zumayev have posted summit pictures from when they reached the top of K2. The pictures were taken at sunset. In on e of them Kaltenbrunner, Zumayev and Pivtsov were together in the one photo. The photos show that all 4 were at the summit at once. Since Kaltenbrunner was the first there, she must have waited a short time for the others to arrive.