My wife's Sister

My wife Katherine 31 had severe complications with the birth of our third child Alison and was unable to have any more children as a result. That wasn't a problem, but she was unable to much at all and that included sex and was bedridden for months. Her only sister Michele 34 single had lost her job in a company collapse and she came to live with us to help out. I'm Maxwell 32 (Max) run my own business and doing fairly well, having Michele come and take over the house and look after the children was a great relief to me. Michelle wasn't in any relationship and didn't much or at all, as far as I knew. Michele looked after Katherine and the children, I offered to pay her for doing it, but she refused. Saying it was her family duty, but I insisted she gets anything she needed on us. Shortly after Michele moved in she and Katherine were as the saying goes as thick as thieves. But they had always been close and I didn't concern myself with that. I told Katherine to make sure Michele got everything she wanted or needed. Katherine replied I make sure she does and I left it at that. A month after Michele moved in with us. Katherine asked to speak to me privately and Michele took the children and our dog for a walk. Once alone except for baby Alison Katherine told that Michele wanted something and Katherine wanted her to have it. I asked what does she want and was told a baby of her own. I asked what's stopping her and was told Michele does have much luck with men and both Katherine and Michelle were wondering if I would father her baby. I was in shock at first and could only reply why me, Katherine said it would be better than donor sperm and we would know who the father is. Still, in shock, I said I would think about it. A couple of days later Katherine asked if I had made up my mind, I said I'm not sure, I would like to help Michele and than again think it would make everything awkward as well. How I was asked, I replied that's it in a nutshell. How do I deliver the sperm, in a jar or by intercourse? What would you prefer Katherine than asked, I'm not sure it would Michele decision I think. Katherine called out to Michelle and she came into the bedroom and Katherine her how she what to get pregnant. Whatever you think is best she replied, Katherine, replied straight sex it is then and you can start sleeping with us in our bed from tonight. Michelle said okay and left the room, I was in shock I think and Katherine then told it would better if we were all involved from the start and sleeping together would be best. Realizing I didn't really have a choice now I agreed and I started fucking Michelle that night and after a month, Katherine was able to join in and after 3 months Michelle was confirmed as pregnant. I expected her to return to her own room, but she stayed with us and still does three years and 2 children later.