Have one of the kids not check in with you and wife. (oldest). Then an hour later, either you or wife go down "for walk" and come back with him. It will usually work. Downside is being kicked out. Other alternative, there are multiple student/youth hostils in Paris by the Sorbonne esp. If 19 yo has international student id, let him (or the 19 and 16 yo both ( stay there). That is probably the best option and they would have fun
https://www.thestudenthotel.com/paris/
https://www.tripadvisor.com/HotelsLi...p10850759.html
https://www.hostelworld.com/hostels/...kMLw&gclsrc=ds