Boys & Girls, the Saga continues, crossing more family lines. This story is a note that I'm not dead yet. And it is a history-making event--Losgud's first follow-up, sequelesque piece. You do need to have read the original "Tandem" to catch all the nuances in this "Extra". If not, smart readers will catch on fast enough.
After her divorce, horny mom runs around teasing and tormenting her horny son as they spend the summer drifting down river in a house boat. Here, mom teaches her teenage son all about sex. They eventually meet a father and teenage daughter also drifting down the river and decided to make it a foursome for the rest of the summer.
An adult brother and sister (with flashbacks to their teen years) and his two teen daughters and their life together, swinging with neighbors, until they come to realize that they are more than just brother and sister. Note there is bisexual male/male sex and some watersports.