The Music Demon by Victoria Danann

The first time Lyric heard Shivaun’s name he knew he’d kidnapped the wrong O’Malley twin.
The first time Shivaun saw Lyric, she wished he’d taken her instead of her sister.
The epic saga of Black Swan and all the lives it touches, human and otherwise, continues with Lyric’s desperate courtship of newly minted demon, Shivaun O’Malley. Meanwhile, Black Swan is discovering that the creation of demons, accidental or otherwise, may interfere with the natural order of things in disastrous ways. Particularly when those demons are female!
From Hunter’s Abbey, Edinburgh, Scotia in present times to the Monterey Music Festival of 1967, this tale weaves a time travel adventure that will have you wishing you could catch the eye of a music demon and be part of the Summer of Love.