Possible to edit mocap animation imported to armature?

Hi…

I recently use Brekel and kinect to capture animation in bvh format. It is not perfect with some weird posture on “some” frames. I imported it to armature that i created using rigify bones but i create my own IK constraint(w/o using generate the rigify setup). In order to import the bvh into the armature i have to turn off the IK and its works. But later on, if i wish to edit some animation by turning IK back on, the animation is ruined. Anyway to fix the bone animation?

Thanks