There is no way Jackson would be able to drive to Ohio without a chaperone. I could see Jill keeping quiet about Jackson himself.
If there was a chaperone that Jill could exploit, we would know about it. There would be a pic with a Dingus, or proof in the background of a picture... something!
I also question where they would have met in recent times. I don’t recall any separate Duggars at the Nurptials. If it was something innocent like Anna & Josh and a few Duggars helped Nurie move, we would have heard about it.
Jill, is that you?