Donna

"How about you, Sis?"
"Fuck you," she says, tears in her eyes.
"He already did," Donna says sharply.
"True. If she keeps up that backtalk, I'll do it again- in her ass!"

Your Stepsister gasps.

"I'm not finished. Then Ms. Tan here will fuck your ass. Then Donna will get her turn. And, if you're still acting up, then I'll fuck your pussy while she fucks your ass. So... anything else to say?"
She shakes her head nervously, her eyes full of fear.
"Good. Then let's not reward her bad behavior. You'll get fucked by her first, Donna."
"Thank you, Master. May I pick how she fucks me this one time?"
"You may. I appreciate you putting my bitch of a Stepsister in my grasp."
"Thank you. So..."

She scurries over to your Stepsister and climbs on the stool, mounting her with that tight ass facing you and Ms. Tan.

"Please fuck me."
You give Ms. Tan a spank and she goes over to do what she was commanded to.
With a little bit of work, she gets the strap on inside of Donna's wet pussy and starts to fuck her.

The Teacher is not used to using a strap on with another woman- at least not in this position. She's made Students use it on her, so she just does her best to remember how they made her cum.

"You were OOH so nice at first," Donna says, mid-fuck, "You said that you'd please me and *grunt* keep me safe. What a lying bitch. He pleased me...just like he pleased you. I OOH YEAH saw how wet you are. So naughty."

She puts her hand on your Stepsister's mouth as a gag and then kisses it, teasing her with what she wants.

As for you, you're hard as hell.
You give Candace a look.
She locks eyes.