Hi,
What is the point of origin, which necessitates such a lengthy stopover in Doha? If there is a later departure from your original point of origin which would provide a shorter connection time with the outbound from DOH to FCO, then the airline is not liable for hotel accommodation if your party has elected to take an earlier flight.
Also, was the booking made with a Travel Agent, or with the airline directly? If it's the former, then perhaps they have forgotte to update the booking details with accommodation request?
Finally, what is the booking class that appears on your family's tickets? Is it sub-load or ID fare bookings?
Thanks,
A300Man