Is there a way to add control rig to a skeleton already have animation?


So, I have a character, a guy riding a horse exactly. This character have joints, bind skin and have around 200 frames of animation baked to the joints, it has no control rig. The animation look bad at some frames and I want to fix it and add some more animations to it, but without the control rig I have to animate every single joints which is impossible. Is there a way for me to add control rig to this skeleton without destroying the animation/twist the joints? (I tried to add an IK handle but it immediately twisted the joint.)

I’m learning to rig and animate so my rigging knowledge is basic, I can rig a T-shape character with quick rig tool, have basic knowledge on IK FK, graph editor and time editor, so if you can help me with step by step instruction that will be a great help, thank you!