Hey Nitrus, thanks for your comment!
I'm a composer myself, although it is not my full time job, but I think I also understand the way Yoko Kanno works when she "reuses" some parts of a music or a whole music.
But it's delicate to say she should have to communicate with the concerned artists, because she would certainly have been refused or asked for some money, and she would have certainly declined the offer, and nobody would never have known her versions.
I believe anyone should be able to write the music he wants, and I like to think of a stolen music as a tribute, especially because Yoko Kanno almost always make another piece of music out of another one. But my point is that actually she makes a new original music every time (I have to add "almost" because there are awkward exceptions).
For example I'd like to speak a little about Cyberbird, because this is one of the most delicate "reusing" she made, but I don't think her work is shameful.
What is true is that it is insanely similar to Battersea from Hooverphonic, except her strings arrangement and recording are far better, and the way she mixed all her Gabriela Robin voices altogether is genius. There's also this silent passage which is not in the original version (she made a 6 minutes song out of a 4 minutes one, so that's a good thing there are some original passages too), and her gibberish melts better with the music than the English lyrics.
But, the structure of the song is different (Cyberbird begins directly with all the strings and the voices for example) and the main melody is very different (just the first notes of the vocal part are the same), enough for me to say it's not a copy, or even a better copy. It's a new original music, very strangely sounding like the original one, but it's not a copy. She may have reused the same chords succession (while actually she did a few adjustments), but she did almost everything again, she composed again a good part of it, and she arranged everything with her style (and recorded a complex chorus with only her voice...).
There's also Heaven's not Enough which shares only the same 4 repetitive notes with Craig Armstrong's Wake Up In New York, but you cannot really say there's plagiarism (except she reused tons of things in that album so actually we know it's not a coincidence).
Actually, I'd say "plagiarism" when a person just takes a song and re-records it without doing anything, and especially if the same structure, vocal melody and lyrics are conserved. it's something hard to tell, but I'm convinced Yoko Kanno always works from A to Z even when she reuses another music.
After, concerning the music you mentioned, it's really possible she got inspired after listening to Morning in Montana, it's difficult to be sure though, but it's different enough for me not to be concerned.
Another interesting fact I found out is that usually experienced musicians and especially composers don't really accuse Yoko Kanno of plagiarism whereas other persons will do that more easily. I think musicians all know that you never writes a music out of nothing, you always have something in your head like the last music you liked or listened to, or a music you want to create the same atmosphere. And eventually, in the end, it will result in something totally different, but sometimes you want to try using the same chords and the same ideas the original music was created with, and it sounds (more or less) a bit alike.
I also remember watching an interview from Cowboy Bebop when she said that she often listens to other songs and when she likes something she just takes it and tries to use it. It's said with such innocence it's really funny and shameful.
May I ask you something concerning your work? Are you a professional, and if that's the case would you mind sharing with us some of your works?
Concerning your friend, I'm really intrigued, of course that would be great if he/she shares with us some interesting facts he/she had when working with Yoko Kanno, especially concerning this aspect of her works.