My sister the lesbian

My sister Joan 29 is a lesbian and is having an affair with my wife Gale 32. Gale is bi-sexual and she seduced Joan in December last year, but she first asked me if I would mind. I said go for it and she did, Joan has always been a very quiet person and I knew that she lusted after women from about the time I found out about sex and lesbians. Joan always looked at the females and didn't look at the males at all. But she was too shy to approach the women she fancied, I saw her playing with herself a lot as we grew to adulthood. I met Gale and we hit it off and married two years later and now have two children with another on the way. Joan had moved to the city for work and was staying with us until she found her own place. I went away on a business trip and went I return two days, Gale told me that Joan has a sweet pussy and I should try it and keep her living with us. I asked did she have any trouble seducing Joan, no waited till she heard Joan masturbating and joined her in her bed and took it from there. Gale said that I should go out till after 9 pm and return and catch her and Joan in bed together and then join in with them. Fucking Gale first and then Joan after we had both worked on her. I said okay and done as suggested. I returned twenty minutes after 9 pm and sue enough Gale had Joan licking her out and not wanting to change positions she pointed to Joan ass indicated I fuck her first. So I got naked and joined them on the bed and proceed to feel up Joan, who was so involved with Gale didn't realize I was doing the feeling. She was very wet and so I mounted her and she didn't realize for a couple of minutes she was being fucked and then once she realized she was being fucked and found out it was me. She stopped lick Gale and Gale told to relax and enjoy and go back to licking her out (Gale). I blew my whole load into Joan and then Gale took over pleasing Joan and I mounted Gale. After we had finished Gale spoke with Joan telling her it was only right that I fucked her as she was doing her (Gale). Joan was still a bit shaken and Gale told her they need not hide their relationship now I knew and had joined in. So after a little time to think it all over, Joan agreed with Gale and accepted she move into our bed with us. In January Joan found she was pregnant and Gale told her that great and she was thinking of trying for another child also but was waiting for our youngest to turn one in late February. In March Gale and I started trying for another child and had succeeded in April. Joan had a baby girl named Katherine after our mother in late August. Gale is having another boy.