I just woke up to find Katie’s Because lesson, and it’s absolutely beautiful. I think Tiffany and I will try that as a duet and try to incorporate some of the Beatles’ harmonies. Thanks!
If anyone else is thinking about singing the harmony, I’ve found this video really helpful. Thanks to Katie for keeping this in the original key. It would be so much harder otherwise.
To answer Ricky’s question, further research has revealed that it was done in 3 tracks with all three singers singing into the same microphone, so 9 voices.