How can we 確認 that Bambi was actually Walt Disney’s お気に入り ディズニー film as 発言しました によって some people?(read description)

Well that's what I hear, but where exactly is the proof though? I haven't found any biography based stuff like if Walt ever personally mentioned it was his 'favorite'. The only thing I've found is in a Making of Bambi video where two of creators 発言しました that they 'believe' that it was was his favorite, but that's not knowing for sure. Otherwise, they would've 発言しました that it's his お気に入り rather than adding "believe" with it.
I do know that Diane(his only biological daughter) is 発言しました that her お気に入り movie was Fantasia as I heard she even attended a I think it was 70th anniversary of Fantasia.
Any proof あなた have on her father's お気に入り film though?