[Plaster] tells me that the original title of the diary of Anne Frank was "The Annexe", named after the house in which she lived, "The Secret Annexe"[1]. He also mentions that The Annex is a neighbourhood in Toronto, Canada.[2]
In this Twoism thread[3] the sample source of the singing children was discovered. The singing is a slight variation of the Jenny Jones poem. The actual song they sampled is A40 "I've Come To See Your Janie Jonies" on this 1983's Children's Singing Games compilation.[4] You can hear it at 1:59 in this Spotify player.