@demonhunter,
Thanks.
I don't want to get too specific but when my son saw a therapist they would often "play". Essentially they'd just start off playing with toys and the therapist would initiate some kind of (relevant to his problems) conflict and through their toys they'd try to resolve it.
The therapist would offer suggestions to my son about how his "toy" might react differently to get a different response. They'd give that a try. The response would be better and so they would be able to move on in their play.
And the end of the session the therapist would review things that happened with him: "Wasn't it great how when your you said A that my toy said B and then they were able to play again?" -- stuff like that.
It was a really good way for my son to talk about some issues that made him sad, angry and anxious.
I can imagine a child who is dying feels sad, angry and anxious. The fact that their child is dying also make the parent sad, angry and anxious and maybe not quite able to handle the child's worries in the most constructive manner. I can easily see a therapist stepping in to help the child deal with his/her feelings.