Oh, I actually think that someone on MrDots team figured out how to do it with, Melody.
As far as anyone knows, Melody has no relation to her tutor, other than a shared love of music.
The tutor slept around a lot in College, and the one person who he got close to, suddenly left with no explanation and disappeared.
Melody only knows that her father was a musician that her mother knew in college, who also disappeared.
Disappearing is rather easy to do, when you are a musician on tour as a backup musician with a band, and your name is not listed on any posters, isn't it?
Both of them are very attracted to each other, and with each release they come closer to being a couple.
All it would take is for someone to mention her mothers maiden name to have the tutor say, OH SHIT!!!
And if they have already done the deed and are madly in love with each other, and they find out at the same time, they may both decide to agree to bury that knowledge, and stay a couple.
We already have seen that Melody has a very mischievous way of looking at things, so it would be within her character for that to happen.
It would not then be a father or daughter seducing or manipulating the other, but both parties agreeing to it.