Staying and leaning in blending tree without sinking under 0

Hi guys, I want to blend three poses (three animations, 1 frame each): staying, leaning to the right and to the left. The root stays in place, but the skier's hips move down when he leans, as planned. The poses themselves are fine, but while blending it interpolates legs an hips and there are couple of frames where the character has his legs underground. I created animations in Unity, no IKs.

Additional question: when I make animation in Unity (with multiple keys and frames), even when I rotate only one axis in the scene view, the Inspector shows rotation among all of them. So, in the middle of these two keys all kinds of fascinating things happen, going crazy. I assume, it address the euler to quaternions thing. What do I do wrong here? No plag-ins involved, I rotate bones under Armature directly.

Thank you very very much for the response.