It would be great! Didn't understand the feature with nulls really. If it the way as on screen rec , it doesn't work either, because mixamo rig is in different position than my character rig.
As I do now usually is I take mixamo rigged animation and change it with character mixamo rig the way I need. But whenever I need to make parent constraint , I can't do it to mixamo rig anymore and it bring this object jumping issues.