Mum intervenes...

"Honey, are you in there? I collected as much as poss... "

The siblings mother enters the room and freezes as she sees her daughter twice, one of them fingerfucking another woman.

"What? Kate? Who... who is this... and this?!" She points at Kate and her 'father', mistaking her son for her original daughter. More weirdly is, that she is pointing with a big ol' dildo at her daughter and husband. Jake looks at it and get turned on, still horny from your sister trying to get their father pregnant, while she herself is probably getting pregnant from him..

"Uhm... Mom? Well..."

"Ahhhh hmmmmmmm...." Jake is interrupted as his father moans and gets woken up by an orgasm. Kate pulls back her more or less clean fingers and grins like a cat. "Hi Mum, this is Jake, and this is Dad. Surprise!"

While their 'father' is groggily coming back to her senses, Kate gets up and pulls their mom to the crowded bed.

"Kate, stop, wait... explain this!" Her mother tries to stop Kate, but she isn't having it and pushes her on her former husband.

"There you go, kiss your wife. Come on, I have seen your porn stash, oh so much lesbian porn!"

Jakes dad is squinting as his wife lands on top of him, their breasts crushing against each other. "Honey? Hmmmm..."
Still horny from the pills the siblings mother starts kissing her changed husband, their lips making lewd noises.

Kate meanwhile discovers the dildo her mother has dropped as she fell on her former husband. "Ohhh, this is just the right thing now."

She gets on the bed, watching her parents making out, and starts pushing the dildo inside her. Jake meanwhile is very much confused, horny and doesn't know what to do... so he just gets down next to his sister and starts masturbating together with her.

What Kate doesn't know, the dildo she's enthustically thrusting into herself has a little fun addition. It's a squirting dildo, filled to the brim with her fathers still very fertile and warm swimmers.