Open Country by Kaki Warner

Molly McFarlane has rescued her dead sister's children from their nasty step-father and now they are headed for California, where she hopes to get a job using her nursing skills. The train they are riding on derails, killing two and critically injuring a third man, and Molly learns the railroad will give $300 in death benefits to the families of the dead. Seeing an opportunity, she marries the badly injured man, thinking of using the money to finish the children's and her trek west. Well, the man, Hank Wilkins, doesn't die. And he can't remember anything. When Brady Wilkins shows up to see what has happened to Hank, he is surprised to learn that Hank now has a wife and two children. While Hank is recuperating and to assist Brady's wife Jessica, with her pregnancy, Molly settles in at the ranch knowing that sooner or later, everyone will find out what she has done. Warner composes an exciting and entertaining second in the series, a really great read.