The upgrade from threesomes to foursomes came about very naturally.

Once when Mike came to spend a weekend with us, at the occasion of his 56th birthday. The Saturday night, Cathy was with her friend, so, as was now our custom, Mike and I would both accompany Mary to bed and together make love with her. We first had a nice dinner and when we finally went to our bedroom, we were very excited going up the stairs, Mike and I groping under skirts of a shrieking Mary. (We found she had no panties on.)

Just when we were all three naked and starting with more 'serious' business, all of a sudden the door of the bedroom went open. It was Cathy, and we heard her say, with a little voice, 'Excuse me, but may I join you?' We immediately understood that something was wrong - later we heard that Cathy and Andy had had a lovers' quarrel.

Not long ago, when we slept together, Cathy had confessed to me that she would so very much like to see her gramp fuck her mother once more, but then not as as a peeping Tom but as a participant, with me there too. When I told this to Mary she no doubt also found the idea exciting, at least she said 'Oh yes, whenever she wants, and then we can let Dad fuck her too, I know that he has been wanting to do so since long and I think that is what she really wants too.' And that is what I thought too.

So I was not at all surprised when my hot Mary now without any hesitation answered to Cathy 'Yes, Cathypuss, come in and join us, but first make yourself decent and undress please!'

Mike already being busily licking Mary's cunt, Cathy when she was naked joined me and I started licking her cunt. But Cathy, absent-mindedly stroking my head, just looked at what Mike and Mary were doing, obviously she was fascinated by Mike's demonstration of fatherly love. And I noticed that Mike, while continuing to excite Mary, also kept an eye, or even two eyes and both his ears, on what I was doing to Cathy. Also Mary noticed his interest for his granddaughter and so at a certain moment she said "Don't you want to find how Cathy feels and tastes, dad?"....(cont)