Wife and sister share
After we had been married for four years my wife's spunky younger sister came to stay, it was not long and I was knocking her off surprisingly with my wife's permission, we were sharing never a threesome, they both liked vaginal, anal and oral so I had a great time. Three years later she met a good guy, married and moved to another city, she comes down once every year for a week on her own early December we all call it my Xmas present and I can tell you she can hardly walk when it's time to leave, my wife always says "well you will just have to shag this old bag for another twelve months" I don't mind she still throws a fantastic leg over and is so very nice, I love her so much
Sounds like you have such an understanding, lovely wife and she certainly has a fabulous young sister they are obviously happy to keep it in the family, I hope the sisters husband gets all the sex he needs vaginal, oral and anal, you better stay off it for a while so you can give your wife a full sac in the New Year