After posting I went online and found an article posted by transport Canada. There are apparently rear-facing seats that go up to 45 lbs., however there is no mention of the height if the child being so long the knees were in the chest, only about feet touching the back of the seat. But they also mention about the expiry date of car seats, which is typically 5 years. If this little girl is 4 and this is the seat they've had since she was born it will be expiring soon, which is another concern other than how she fits in the seat. But the transport Canada article also says not to rush to move a child to the next stage, to only move to next stage once the child is at the manufacturer's weight and height limits. Maybe just bring it up casually, mention you had seen them put her in a rear-facing seat and say 'wow that must be one of the rear-facing ones that go up to 45 lbs?" And casually ask about what the height restrictions are when the weight is so high. If they have no clue what the height restriction is maybe it will make them realize to look at their manual to check or something. Maybe they don't realize there is a height and only a weight or something.