Miwaku no Dokushin Kizoku

In the Miwaku no Dokushin Kizoku (Bachelor Cousins) series:

V.1 - Kojou ni Tsudou Ai (To Marry McKenzie)
Eligible, elusive...and engaged!

Logan McKenzie liked his life exactly how it was -- with no surprises, and without a wife.

Then Logan learned his mother was about to marry for the third time, and that Darcy, his very pretty stepsister-to-be, was in danger of being hurt by that marriage. So he found himself getting involved -- not only in trying to prevent the forthcoming nuptials, but with Darcy herself...and his carefully controlled existence was turned upside down!
- from FictionDB

V.2 - Nazomeita Bijo (To Marry McCloud)
Fergus McCloud couldn't quite remember how he'd first met Chloe Fox...but circumstances indicated that they'd slept together pretty soon afterward! Actually, they hadn't. But Chloe's mission was to persuade Fergus not to publish a book that would ruin her family. What better way than to prolong the pretense of their being lovers? Only, Fergus wanted to rediscover the delights of their night "together"—and he intended to be present this time...in mind as well as body!

V.3 - Ubawareta Kuchibiru (To Marry McAllister)
Brice McAllister, the world's renowned artist, instantly falls for Sabina as soon as he meets the gorgeous supermodel's gaze. He has agreed to paint her portrait only to quiet the insistent billionaire who demanded Brice to paint his fiancee's portrait at any price. The meeting arouses his desire to draw Sabina. However, once he starts to work on the portrait, Sabina does not hide her fear and avoids his gaze. It is as if she believes allowing him to draw her is a sin...

English publication via Renta!, part 2