Stan and Haley got locked in the basement by Roger who ended up forgetting they was in there after a few hours Haley starting to yell for help hoping someone would hear her only for Stan to tell he made the basement soundproof it got to hot and Haley and Stan removed some clothes to keep cool in just their underwear they couldn't control themselves and ended up fucking
When they finally got out they said no one can ever know what happened and then immediately started making out and went to Haley's room to go again it went on for a few days until Steve caught them he told them he wants to fuck Haley and Francine Stan and Haley who just finished agreed
Is your choice how they get Francine to join and if Francine and Haley have lesbian sex or not