Sisters both Pregnant

I'm Dennis 29 and I've been dating Karen 26 and now we're getting married in February, also she tested positive to being pregnant late last month. I've also been seeing her sister Mary 24 and she has now tested positive to being pregnant. I was stunned at first and then shocked by Karen who wasn't at all concerned by me getting her sister Mary pregnant. She had asked her sister to date me also so I wouldn't stray (her words) and wasn't concerned by me fucking her sister. Almost 2 weeks after Karen tested positive, Mary tested herself and it was also positive and both are now confirmed positive by their doctor. As far Karen is concerned nothing has changed and we are still to marry in the coming weeks and I've purchased a house for us and Mary is to live with us also. We've even had several threesomes since both were confirmed a pregnant. Karen has her own career and Mary didn't do well at school and I've been told that Mary will be my home mom and Karen will continue with her career after the birth of our child. I work for my family firm and am still a bit shocked by how happy both sisters are and how they just accept sharing me sexually. But they have always been very close and I'm happy they are happy.