Z.B.
I'm confused. Baby in sling, bigwheel in one had, his hand (or wrist) in the other. I have a very strong (seriously strong) 4 years old, and there have been times when I have started out dragging him. But he learns pretty quickly that I'm not going to let go and walks with me. He might continue trying to get away, but I hold on.
Was holding his hand (or wrist) not an option?