If you didn't figure it out from me saying over and over that they assume it was permanent... It isn't.
Then a week before the one year anniversary of swap day, the news announces that they have figured out what caused the swap, the comet is coming back around again, and exactly 1 year after swap day, everyone should be swapped back.
They have one week to come to terms with all the changes they have made to eachother. The son got his mom's body pregnant again and now is breastfeeding two babies which she has much less of a connection to considering she didn't give birth to either of them.
The dad lost his daughter's virginity to his son and is an S&M cock whore addicted to a shota trap.
The daughter got her dad's body in the best shape of his life but also gave him herpes at least, and since he is so used to being a young subby woman now, getting his burly body and giant cock back will really frustrate him. Not to mention the whole time, his boss who is a woman with a man's body has been sexually dominating him at work too!
And the mom has given her son 10 months of female hormones and a breast augmentation. Also the mom has been seeing her best friend who stayed a woman the whole time, and they have occasionally teamed up to dom her husband.
With their old bodies back, the son drops out of school to become a full time mom and tries so hard to breastfeed the babies that he does eventually induce lactation, so mom and sister stop helping. The mom threatens divorce and plans to marry her lesbian friend. The dad goes into full time chastity and becomes a bitch to his boss, his wife, and even his son, who he begs for cock. The daughter starts taking steroids and weight lifting and becomes more jacked than ever including pumping her clit and wearing strap ons to fuck her boyfriend and her former girl friends.
That is where I am going with this, and the fucked up shit I want to do to this family.