I thought room of requirement was invented in Harry Potter, which would actually lead to a plausible theory about Jack's house.
How can a bungalow have stairs? Magic. How can you have a giant shed and studio and multiple rooms and still not have space? Well, some mornings you wake up and the bungalow has decided to shuffle around a bit, narrowing corridors and shrinking spaces, and the shed isn't where you thought it was. (Sometimes pets and small boys also go missing for a few days) How can you take a picture of your son's bedroom when he's asleep, but there's daylight glaring through the curtains? Well, you know, Jackwarts doesn't operate according to normal schemes of sunrise, that's why it's hard for her to get anywhere on time. It's slightly removed from the physical and temporal dimensions we understand.
Suddenly everything makes more sense. How can Jack have so much room, yet no room? How can she have no food, and yet a store cupboard that seems to constantly replenish itself with the most obscure and curious combinations? Because whenever she opens it, it's restocked itself according to its own whims. It's Tuesday, I wonder what the cupboard has for us today! Can of prunes, chicken liver, Fanta. Quick, draw up a new meal plan! This explains her 'MO' of creativity with unlikely ingredients; she's adapting to the idiosyncrasies of her haunted mansion. How is that hare statue in this room today, and that room tomorrow? Why is that elephant statue always in the corner of a picture? Well, she turns her back and they seem to scuttle around mischievously, like thrift-sale versions of Cogsworth and Lumiere.
Needs more work but I think I can get an 8-book children's fantasy series from this
It all makes sense now! 