As you might know, Kling Motion Control is not free. I found a platform that lets you do it with free credits.
Step 1: Create your original video
Step 2: Screenshot 1st frame of your original video as an image
Step 3: Upload that image to Nano Banana Pro to change the scene (e.g. make it underwater), 2nd image is created
Step 4: Upload that 2nd image + your original video, Use motion control
Free member - Full prompt, tool and free guide:
Premium member - full guide and prompt