Matching the motion of separate bones issue

New to Unreal Engine so apologies if the answer is obvious. I am trying to convert animations from Mixamo to UE5’s third person character but am unable to create motion for the IK foot bones that exist in the third person character skeleton (the goal of doing such is to keep the IK foot bones in the same position as the actual foot bones so the third person character IK system works properly). I have added a root node from the base Mixamo rig but havent been able to successfully add motion for the IK foot bones. Any help in this matter would be greatly appreciated.