Just so you know, the word had already appeared in a 1959 song by Alan Holmes & His New Tones, called Supercalafajalistickespeealadojus. The authors (Patricia Smith a.k.a. Gloria Parker, Don Fenton) sued Disney but lost. Disney claimed the word was already a slang term but no evidence exists of this; and the Sherman Brothers, who wrote Mary Poppins' OST, still claim they 'invented' the word, mostly out of double-talk, as a portmanteau of different words coming from different languages. Thus it sounds clear to me that the Shermans DID crib and then unashamedly invented a story about it.