The Hidden Family Charles Stross
Miriam, a hip tech journalist from Boston, discovered her alternate world relatives in The Family Trade, and with them an elite identity she didn't know was hers. Now, in order to avoid a slippery slope down to an unmarked grave, Miriam, known as Lady Helge to the Family, starts applying modern business practices and scientific knowledge to a trade dominated by mercantilists - with unexpected consequences for three different time lines, including the quasi-Victorian one exploited by the hidden family.