The Sumo Deadlift is a much different movement than the Conventional Deadlift. Set up with feet outside shoulders and toes pointed out. Hold the bar and pull the hips down & chest up. This will create tension in the hips and a solid upright position. Drive the knees out over the toes, to increase this tension. Adjust the feet so tha the tshins are vertical in this bottom position.
WIHTE-ORANGE should focus on tightening up this new movement and getting into the correct positions. BLUE- PURPLE+ can push the weight a bit, but focus on smoothing out the technique first.