Silvie, my sexy mother-in-law, was so desperate for a replay that she booked her daughters, Tracey, my wife, and her sister Jane, in at a spa resort for a weekend break. This came about two months after the first sexual liaison, and this was about to be as good, if not better, than before. Tracey and Jane left on Friday afternoon and were not expected back until Monday afternoon. This left us plenty of free time to have s...