If I were the older couple, I'd hesitate to make a major deal of it. Travel in/out of the country as long as possible (perhaps forever) paying the overstay fee. If that becomes impossible, then perhaps pursue other avenues if intent on remaining here. Otherwise, I'm not sure I'd bring myself to the attention of any powers that could a) potentially kick me out or b) prevent my re-entry on a tourist visa. Or, discretely have an attorney check into it.