Originally Posted by
Oxon Flyer
Wecloem to Flyertalk and the Starwood forum
allenmchan 
FWIW, I had a look and found these Starwood hotels that can legitimately accommodate 4 adults in one room :
London : Le Méridien Piccadilly : Club Room, 2 double beds
London : Sheraton Skyline : Family Room : 2 double beds
Paris : The Westin Paris - Vendôme : Presidential Suite.
Paris : Prince de Galles : Mosaic Suite; Appartement Parisien (which is only Eur12,160 per night
)
Paris : Le Méridien Etoile : Senior Suite; Executive Suite.
But the OP still has two obstacles, namely:
1) None of those rooms are available for Award bookings, which is what he wants.
2) No more than 2 guests are permitted to stay in an Award room.
I think it's a really badly-conceived plan that the OP has thought up, he's probably just not used to travelling in Europe.
The best that he can aim for is to pay for a standard room for his wife and himself and to redeem points for a second room for his in-laws.
Which will also ensure that the vacation doesn't just become an endless queue for the bathroom.