AFAIK there has always been a discrepancy between the website and what they allow. There are a few examples of this in the thread way back. The website will show that 3 or 4 can stay in a room under the configurations you have mentioned but they will supposedly charge for the 4th person (the child) if 2+2 or the 3rd adult too. I think this is why they do not enforce the policy. Best to check with the reservations department before you make your booking and if you can post back here I'll add the info to the wiki.