In the Billionaires' Brides (Ouji ni Miserarete) series: 6z3in

V.1 - Kiseki no Deai (The Italian Prince's Pregnant Bride)
When a chance encounter has Prince Nicolo Barbieri bump into Aimee Black, he's met with a rather rude and angry woman. When they run into each other again at a dance club, they consider it a coincidence. When he finds out that her grandfather owns a company he's trying to take over, he starts to wonder: Is this all part of some bigger plan? When she shows up months later pregnant with his child, he has to ask himself if it’s strategy or fate that keeps bringing them back together.

V.2 - Ai ni Obieru Hanayome (The Greek Prince's Chosen Wife)
Ivy Madison claims she's pregnant with Prince Damian Aristedes' baby, but he's never even met her!
Is she just another gold digger, exploiting his wish for a son and heir? But Ivy is expecting Damian's child – as a surrogate mother! The arrogant Greek is furious, but he's not about to let Ivy go. After all, he missed the pleasure of bedding her to conceive his baby. .

V.3 - Andalucia no Ichiya (The Spanish Prince's Virgin Bride)
“Go to Texas. There you’ll find what you’re looking for.” With this mysterious message from his grandfather Felix Reyes, Lucas sets off on a journey and stumbles upon a shocking truth. Before he died, his grandfather had orchestrated Lucas’s betrothal to Alyssa, a friend’s daughter. Lucas didn’t want to give up the bachelor life and had no interest in marriage…and neither did Alyssa. When Lucas appears out of nowhere, Alyssa knows she can’t marry someone so arrogant. However, since half the deed to her ranch belongs to the Reyes family, if she refuses the marriage, she must also let go of her beloved home…