I am 32 years old and I have a wonderful wife who is now 28 years old. My sister in law who is 30 years old just got married last year but she couldn’t have any kids as her husband’s sperms do not contain any tail. It was a pity as they really tried hard to have a child and they were devastated when they found out the reason. The doctor said the only way for her to get pregnant is via implantation of sperm from the sperm bank which will cost a lot of money. Being young and newly weds, they didn’t have the financial capability to do so. My sister in law and her husband came to me secretly as they came up with a plan, which is for me to impregnate her. Initially I was against it, but they kept begging me. The plan was for me to just masturbate and slide it in her right before I came. I agreed eventually as I felt there was going to be minimal sexual interaction. So the big day came when my wife went away for business trip. They chose to do it at night so it will be dim. I was stroking my cock in the dark while she waited. When I wanted to cum, I tried to slide it in her pussy but I couldn’t make it in time as she was still dry and I shot just on her pussy and not inside. We were hoping it will work but she did not get pregnant. After consulting with some of their doctor friends, getting pregnant is not that simple. They mentioned that the mind plays a big role and the method that we use might not be working too well. During my wife’s next business trip, she will be away for a week. This time, we did it differently, we made it more intimate. It started off with her husband undressing, followed by me. He was already rock hard and he boasts a 7.5” cock, it’s such a pity that there’s some problems with his sperms. Thinking what’s going to happen next got my cock hard to 6” and I am way thicker than him (maybe that’s why I couldn’t push it in time the previous round). I can see my sister in law blushing and she started to undress. She took off the top and slid her skirt off. She was there in her matching bra and knickers and I must say, she really have an amazing body. Her boobs should be a 34C and she has a tight ass. She was shy so her husband helped to take off her bra and knickers. Her pussy is completely shaved and her pussy lips looks tight. He starts to kiss her while I watch as I don’t know what to do. He then proceeded to touch her pussy and fingers her. He starts to get her wet and he gets her to kneel on the floor to suck his cock. The entire scene was so hot and slowly she was less shy and she sucked his cock faster. He lays her on the bed and starts licking her pussy as she starts to make soft moans. He then proceeded to slide his 7.5” cock into her and stars fucking her missionary style. After 10 mins, he flips her over and put her on all fours. He asked me to come to them and asked her to suck my cock. It was awkward but the feeling of her warm lips wrapping around my thick 6” cock got me so turned on. For once she spoke out, commenting on how thick my cock is and before she could say anything further, her husband slid his cock into her and fucked her doggy style. She continue to suck my cock for another 10 mins and he pulled out from her and told me it’s my turn. I froze and didn’t know what to do as the awkwardness set in again. Her husband assured me it was alright so I took his place, positioned my cock at her pussy entrance and tried to push it in. It was quite difficult as she was tight, and she kept telling me to go slow as I was quite thick. After a few attempts, my cock head slid in and she asked me to wait so she could get used to the thickness. She started to push her hips backwards so my cock will slide in further and we started fucking. She was really hot and I couldn’t help myself but to start playing with her nice 34C tits. She kept saying “oh gosh, u r so thick, really stretching me out, I haven’t had this thick cock before”. She suddenly took control and said she wanted to be on top. I lay on the bed while she slid my cock into her pussy and impaled onto my thick cock. She then took her husbands cock into her mouth. We fucked for like 2 hours with me and her husband rotating to fuck her. I came 3 times and we continued to fuck everyday. On the 5th day, I was ramming my sister in law doggy missionary style with her legs over my shoulders when suddenly my wife came in. Her business trip got cut short and we were all in shocked. We tried to explain to her what was going on and after some long explanation and my sister in law produced the results from the doctor, only did my wife calmed down. I suggested that we call it a day as a sign of respect to my wife but to my surprise, my wife asked us to continue but she insisted that she should be there. As I continue to fuck her sister, she suddenly grabbed hold of her brother in laws cock and started sucking it. She undressed and it suddenly became a 4 person sexual encounter. He laid my wife on the bed and fucked her missionary style. He was really ramming his whole 7.5” into my wife and she was moaning and shouting. He flipped her over and started fucking my wife doggy style. My wife started to shout “I’m cumming, you are reaching so deep, so long....”. After 30 mins, he started to fuck my wife harder and I knew he was cumming. Be shot inside my wife as he was sure he won’t impregnate her due to his sperm problems. After 15 mins, he got hard again and he came to fuck his own wife while I fucked my wife. This time he pulled his cock out before he came and starter to shoot streams of cum all over his wife and my wife. I continued to fuck my wife while we were all in a huge mess and my wife asked me to cum in her sister and not waste the sperms. I slid out and went over to fuck my sister in law and came in her. After the sexual encounter, it was an awkward moment. We cleaned up and we were really quiet. After a while we started chatting and sharing. Both of the ladies were really satisfied as our cocks were different. My cock was only 6” but very thick while my brother in law lacked the thickness but it was really long at 7.5”. We started to talk further and my sister I law commented that it was really hot feeling so stretched while my wife admitted that it felt really good when the cock reached so deep as she never had someone so long before and it was reaching places I couldn’t. Both of them agreed that it was good rotating from long and thick as the pussy keeps getting pounded by different cocks. We got really horny and the sex started again with my sister in law riding me reverse cowgirl while my wife rode him cowgirl. Well, my sister in law didn’t get pregnant, and we did not try it again. Eventually they managed to save up and got a twins through artificially planting of the sperm. We never talked about it anymore till this day.