Adult children's stories

Currently reading the girls Jacqueline Wilson's Vicky Angel. I'm not sure what to think about her books, peppered us they are with death, grief, divorced parents, abuse and mental illness. Are our 7 and 9 year olds too young for this kind of grim reality? Vicky Angel is about two girls: one killed in a road accident who reappears as a funny, mischievous ghost, the other her grieving best friend. The previous book we read was The Longest Whale Song about a girl's (successful, thankfully!) attempt to bring her mother out of a coma. They're both funny and sad in equal measure, and I guess deal with real things, prepare them for real life. (When I was that age, the limits of reality were probably Arthur Ransome and Tintin). Wilson is apparently the most borrowed author in British libraries. Anyway, our two really like them so I guess it's fine.