I was basically saying about the letter if it is Michael's that it sound like the letter could have been about Diana. Due to the langauge in the letter like "I dont regret it" and "Why did you run away" I said that the 4th child statement could have been about the idea of them having a child together. Hence, Diana had 3 girls and the 4th child would have been his and Diana's I guess the 4th child referece mean what could have been in their relationship like a symbol.