For this piece I used pianoteq with the piano tuned to Pythagorean tuning which is a just intonation tuning that is based on pure fifths at the expense of a couple ‘wolf notes’
I composed Natalie, exported her voice and re-tuned in Melodyne to Pythagorean. Then I composed the piano part around her vocal line with some touch ups after a few tries until I found something I liked.
For the tuning curious wikipedia Pythaorean Tuning