Using NLA to correct Motion Capture Anims?

So here’s the problem I’m faced with – I have a character I’m exporting to Unity. I have applied a custom Mocap walk cycle so that she is walking in high-heels. But I’m having issues, as you can see from the attached images: The legs cross over each other way too much, the feet sink into the floor somewhat, and the arms are not sufficiently clear of the rest of the body, so the hand go through the hips.

My question is, what is the best strategy for fixing a motion capture anim like this? I thought it could be done with the NLA with “additive” strips, which is new to me, and when I’ve tried to follow tutorials on YouTube, I get unpredictable results, including massive distortion of the mesh, so that she suddenly looks like she’s from Omicron Persei 8, or at the other extreme, the animation getting cancelled out all together.

Can anyone suggest helpful tutorials or resources for using NLA to do this? Or is there a better way to tweak MoCap files? Am I better off trying to fix the problem in Unity rather than Blender?

Thanks ahead.

Dave