I think you and your family would enjoy being at the Hilton on Orchard Road, rather than isolated at the Conrad. The latter is very nice, but located out of the way -- imagine the Terrace de la Chaudiere complex and the hotel there vis a vis downtown Ottawa, and you'll get an idea -- and a long walk to the MRT/metro. As to room size, both have relatively large ones that are equivilent to most NAmerican city centre properties. Conrad probably has the edge here. So just book a room with 2 Queen beds and don't even mention your child. Let them fix that up when you arrive if you think the bed is too small to accommodate you and your wife in one, your daughter in the other. You are only causing more problems than are necessary trying to deal with this matter through the res agent.