Taming the Scotsman
After this book the only one of the brothers left unmarried is Lochlan, and he's dealt with in the next book.
While a good and extremely funny read, I found this to be the most improbable of Kinley Macgregor's books that I've read so far. Things moved a little too fast I guess. On the other hand, the characters are fun and full of life. Also we see more about all of the brothers' lives and some of the events that shaped them.
I'm not saying much more as there's a really nice cliff-hanger in the ending of this story.
Kinley Macgregor under either name is the only Romance genre author I've bought and read books from. If you're looking for a guaranteed happy ending, her books are for you.