I am so sorry to hear about your neice canoehead. I don't really know how what to tell you - what ya'll have done sounds helpful. If they don't have cellphones, providing them with phone cards they can use from the hospital is great.
I personally had a friend who had two - yes I said two - of their children diagnosed with Neuroblastoma. I can't remember their exact ages at the time, but one was 2, and the other was 4 I believe. They were diagnosed just months apart. The older child, a little boy was Stage IV, also and is cancer free today
. Here is the website - if you read his journal you will find out a little bit of what he went through. He eventually had a BMT, but today is a beautiful red-headed ball of energy. http://www2.caringbridge.org/ar/elijah/
His sister is also cancer free, but did not have such a great outcome. She had problems from infection from chemo, and suffered brain damage (long story). This was not directly related to Neuroblastoma, just chemo related problems in general, but might not be the most encouraging thing to read right now.
As for my friend, I gave her a journal and pen to keep with her at the hospital. She said that was so helpful, because she was able to write down her feelings, and things the doctor said when they come in and out, etc.. She like it so well, she bought some to hand out at the children's hospital to newly diagnosed cancer patients parents. I also kept in touch, and let her know that I was still praying for them, and that I cared. We live in a small community - where everyone knows everyone, but a friend and I arranged a fund raising bake sale in the bank where we worked, and were able to raise $1,000 for them to help with their travel expenses, food, etc or whatever else. When the first child Hosanna was finally coming home from the hospital after many months, a friend and I made a banner for their front porch, put up balloons, and left presents for them to welcome them home. I know these aren't things you can possibly do since you are so many miles away, but just wanted you to see just some of the smaller things we did, that my friend says she will never forget. Maybe you can come up with ideas from this.
I pray that your neice responds to therapy, and lives a long and happy life.