Some motorhomes have seatbelts at the dinette. The bolt into the floor under the cusions with the belts coming up between the seat and back. Could you have some added so they could sit at the dinette and be belted in? Ours doesn't have them there, but the sofa and chair have factory installed seatbelts. Have you taken things apart, looked under to see if some are there? When we purchased ours used they weren't used, so the owners had them tucked back thru laying on the floor under the piece of furniture. Just a thought.