I think you are right about Nick exercising his paternal skills. But I can't help but think back to when I was Kelly's age. If a grown man who was a friend of daddy's had told me to get undressed and hop into the tub, I would have done a 180 and bolted.

I'm referring to the scene where Nick finally tells Kelly the truth about her parents and sisters death. I think that Kelly's reaction is trumendously unrealistic.
I find this especially puzzling as AM is a guy who usually pays great attention to detail and authenticity. I would count on him consulting with a pediatric psycho-therapist to get pointers on how to keep it realistic, but this can't possibly have been the case here.

Not only was Kelly finally receiving the news of her parents and sisters death, but she had just been involved in a violent hostage-situation with McGear at the PIRA HQ. And don't forget that the death of Kev and his family's death was a particularly gory one in the first place, and that Kelly was a (auditive) witness to it all. I would expect that with all this towering above her, she would have an extreme reaction to extreme circumstances - her having a mental shutdown that would border to autistic behaviour or something of that nature.
Instead, she matter-of-factly goes on about wanting to "be with Nick then", as her parents are gone. This isn't just a far too pragmatic adult mentality to fit a 7-year-old, but it simply boils down to bad writing on AM's part..... (sorry AIB ;)

And another thing: having the skin is his neck split open by a fire-extinguisher (again, referring to the hostage-drama with McGear) would normally require some sewing, wouldn't it?

But hey : it's his first fiction. He's done a good job so far, so a slip now and then isn't the end of the world. :)

Since AM wrote Kelly as a seven-year-old, my position is that she would not fully comprehend the concept of death and its permanence. Also, young children think primarily in terms of the present, so she would not realize that the deaths of her parents and sister meant that she no longer had a future with a family and a permanent home.

And now the research…

Delayed Mourning: For some children, grief may be too great to express. In some cases of acute grief, a child may appear oblivious to the loss. Some experts say that children have a "short sadness span," so you shouldn't expect a long period of grief in most cases.

Source: http://library.adoption.com/Death-Grieving/
Discussing-Death-with-Preschoolers/article/1164/1.html
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Age 2-6 years:
- Often believe that death is reversible, temporary
- May perceive death as a punishment
- Magical thinking that wishes come true (such as guilt that they had negative feeling toward the person who died, and that was the cause of death)

Age 6-11 years:
- Gradual understanding of irreversibility and finality of death
- Concrete reasoning with ability to comprehend cause and effect relationship

Children need lots of reassurance that they will be loved and cared for by a consistent adult. They also must be assured that they did not cause the death, nor could they have prevented it.


Some children seem to show no emotional response to death, which can be disconcerting to family members.

Some normal behaviors include: shock, crying, sadness, anger, guilt, increased clinginess, disobedience, lack of interest in school, sleep difficulties, decreased appetite, temporary regression to more childish behavior, physical complaints.


Source: www.nlm.nih.gov/medlineplus/ency/
article/001909.htm
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Children are people, and in many ways they react to death like the rest of us. They may feel shock or deny at first that death has occurred. They may feel guilty for not being "good" to the person who died, and they may become depressed. Children often conclude that they somehow caused the death. They may think, "I was bad, so Mommy left," or "I wished my sister would die, and she did."

Children can also react to death in surprising and erratic ways. They may greet the news of a loved one's death with nothing more than a shrug, then express their grief in subtle ways later. They may regress and begin sucking their thumbs, wetting the bed, or otherwise acting like infants.


Source: www.hillfuneral.com/children.html

I haven't read that far ahead since I posted my comments about Kelly's (lack of) reaction (NS is searching his laptop to see what kind of data he managed to copy from the PIRA HQ computer), so I don't know if AM has put in some of the delayed mourning events for Kelly (according to your thurough research) as the story progresses. But I certainly agree with the fact that you've got relevant data to back up your "counter-post".
The parents death aside though -- I would expect Kelly to be more "traumatized" (or influenced at least) by the recent hostage-drama. Keep in mind that she got physically stepped on by both NS and McGear as NS jumped on him to push back the topslide of McGear's 9mm.
Also, I would think that being a witness to a guy (NS) biting off pieces of flesh and skin from another persons face like a wild animal would generate a more substantial reaction on Kelly's part than what is portrayed in the book. It did say that Kelly had probably run away since McGear was no longer holding her in his right hand, but I should think that even all the commotion, shouting, hitting, gunfire etc. etc. alone would be a tough load of inputs to handle for a 7-year-old.

It's hard to argue with scientific data (and you sure found plenty of it), so I suppose a leighman's opinion doesn't stand that much of a chance in any case. I'm not going to dwell too much on this... It would be interesting though to hear if Tabby's got some viewpoints on this - as a professional on the subject.

Looking forward to further reading!