The Wrong Heiress (More Courtesan Chronicles #1.1)
Claudia Dain

Somehow, Lord Redding has chosen the wrong heiress.
There isn't much Elena can do about that, except anticipate life as a bitter spinster, something not likely to improve her disposition, until Elizabeth meets Jamie Caversham in the British Museum.
Jamie sweeps Elizabeth off her feet, Horatio is left adrift, and Elena decides to swoop in and entice him to carry her off to the altar. All Horatio has to do is cooperate and let Elena fall into his lap. Will he or won't he?
A short story set in the Courtesan Chronicles in which Sophia plays a small part.