I've been playing around with the program (Synthesizer V) for about a week now, and I just realized that you can instantly double a track with a different singer with just one click, to get a very realistic choral sound. Then you can slide the notes around on the doubles and get instant harmonies without having to type in the words again. Here's a small test I did this morning, using 4 different AI voices singing together:

https://iradeo.com/station/169468