We had a similar experience with Air Canada when my MIL and nephew (8 year old!) were flying from Winnipeg to Toronto and onwards to Dublin. When we checked in (very early!!!) the seats that were allocated weren't together. They had to wait almost till the last minute before boarding to be reissued new seats together. Not very comforting (not to mention the stress involved) when an 8 year old is sat halfway down the plane from his guardian!