I have noticed that when using most of the rigs, when the pelvis control is rotated the leg setup also is affected a bit. I tried using broken hierarchy, I am sure which should work well to get the change not happening. Can anyone throw some light on the same, I will be glad to know. Thanks. Regards.
Generally speaking, if the pelvis moves, the legs should move (they are attached at the hip... ). Without knowing exactly what you want to accomplish, I'd say try rotating the spine. If that is not what you're after, try adding a joint above the pelvis and attach geometry and other joints.
If you want to capture a quick Jing video and share it to see what your having problems with that is the best way to see it.
Other than that, some rigs put the knee controls under the hips and causes the legs to twist with the pelvis.. sometimes IK with just twist will inherit waist rotation in an odd way but agian, with out visuals its hard to say.
You could have a total broken hierarchy in that the legs don't attach at all to the hips and its up to you as animator to move three controls together to make the hips and legs move.