I’m convinced the boy in the school photo is the same as the boy with mother and father by the christmas tree:
http://starbulletin.com/2007/07/29/news/art4bx.jpg
That kid in the airport photo with the father is not Malik.
http://starbulletin.com/2007/07/29/news/art4bx.jpg
I do not agree with you--his mouth is narrower; his body frame is thinner; his cheek bones are closer together and more pronounced; his hairline is different; and his face is thinner. But, to be fair, in this school picture you post here, Obama is also older.
Although the pictures of the brother when he is older maintain their contrary characteristics.