Prommegger defeated Austrian teammate Ingemar Walder in the men's big final while in the women's at the Olympic test event Kreiner got the better of German Amelie Kober.
In the men's competition, Prommegger recovered from a stumble against Lukas Mathies in the quarter-finals to see off Walder who was almost defeated by Jasey-Jay Anderson in the heats.
Walder was disqualified from the first run of the big final and failed to finish the second handing Prommegger victory and with it the lead at the top of the overall World Cup standings.
With Roland Fischnaller, the winner last time out in Rogla, losing in the heats to parallel slalom world champion Rok Marguc to place ninth overall, Prommegger's win gives him a lead of 610 points over the Italian.
Meanwhile Olympic bronze medallist Kreiner didn't drop a run on the way to the women's big final before defeating Kober over both with Prommegger then completing Austria's success.
Kreiner got the better of Kober by 0.33seconds in the first run and then just 0.04 on the second to likewise move into the top of the World Cup standings.
Her jump up was also added by the previous leader's failings with Caroline Calve ranking down in 14th with Kreiner leading second-placed Ekaterina Tudegesheva by 190 points.