Her Forbidden Bridegroom by Susan Fox
She promised her mother that she'd not get involved with her real
sister, otherwise her mother would tell everybody their secrets.
She works for her real sister and when she is introduced to her step
brother she knows she has to get away from her. The only solution
is for her to pretend to be his wife to be. They go out for dinner
so others will think they are attracted to one another. The mother
was involved with his father. It's quite a mixed up tale as to what
happens next. ( )