ABANDONED. Children's book - trees spreading through pages of the book

[Transit]

I am looking for a book that I read as a child. I think the following describes the book:
-main character is a child
-child's parent is an author. The child's parent wrote books themselves by hand and doodled trees on the edges of the pages
-the book the child's parent wrote was about a kingdom
-something bad was happening to the kingdom and in the real world it was reflected by the doodled trees spreading through the story book and eventually obscuring the story
-I think they lived in an apartment building
-read 1995-1998, published ??? (library had many old books)
-chapter book with limited illustrations

[bookel]

And the year read was ...?

[Transit]

Some more things remembered:
-There was travelling between the storybook world and the real world (main character child and prince in the kingdom)
-They had a neighbour (upstairs I think) who was an older women who would bring them these not very good desserts. The desserts were made from a cookbook that the author had written and were the favourite dessert of the prince in the kingdom.
- I think the author of the story book was the child's mother
-I think the child was a boy
-I think the mother was dead

[Lobstergirl, au gratin]

Transit, are you still looking for this book?

[David]

Could it be Inkheart?

[Lobstergirl, au gratin]

No response in 2+ years. Moving to Abandoned.