I've come to notice over the course of my European travels that the list of available room types that pops up in a search can vary by number of guests/per room. I have seen double/double rooms that only allowed 2 guests/per room, yet I know that many families would find a double/double room perfectly acceptable for say, 2 adults plus one or two children, or in some cases, even 3/4 adults, yet on the website, if you plug in 3 or 4 guests, these room types will not appear, or else when you try to book them for 3/4 persons, it will throw an error message telling you to decrease the number of persons/room and increase the number of rooms to book, before continuing. For instance, a double/double larger room, appx. 430sqft can be reserved for 3/4 persons at the Marriott Champs-Elysées in Paris, yet a double/double larger room at the Shelbourne Renaissance Dublin, cannot be reserved for 3 people, even though the room is spacious and the photo even depicts plenty of open floor space (say for a rollaway), and in fact it permits a rollaway for an extra charge (a room with two double beds, plus one rollaway allowed, yet it can only be reserved for 2 people?)
I decided to reach out to the Dublin property and inquire of this. I received a reply back telling me that they would indeed accommodate 3 persons in that particular room type, and to just go ahead and book the room for 2 people, then shoot them back an email with the confirmation number, and they would update the reservation from 2 guests to 3 guests. This is exactly what was done, thereby saving us some money.
I thought I would just throw this out there in case there are any families who have run into a similarly frustrating situation when attempting to reserve rooms at some of the popular European Marriott properties. The lesson then, is if you find a property that you think would reasonably accommodate 3/4 persons, but the website won't let you book it (or the reservation agents over the phone - I'm convinced that they only see the same things that we do), reach out to the property itself and see what they can do. I'm glad I reached out with an email to guest services at the property, which produced some good results.