I have played the game many, many times through, but I still have four characters that are not unlocked. The first is the character between Mr. Everett and Olivia in the character list. The other three are on the row immeidately below, the row that concludes with Phoebe Ingram. I thought they were the children from the school, but I've met the children many times and the character list hasn't updated. It just shows ???