Well, then. Only one option.
Send in Kisha with Naomi to act as a couple's counselor
"So what's the problem?" Naomi asked, setting a candle on the table and lighting it. It gave off a floral smell.
Both cat-eared sisters immediately start to talk over each other.
"One at a time." Naomi said. "We can only hear one voice at a time. Just a moment." Naomi reached into her bag and pulled out a bright red ruler. "This is the speaking stick. Only the person holding the speaking stick gets to talk. So again, what's going on?" Then she held the stick out to Kisha.
"My sister locked me out of our apartment and doesn't want to have sex with me!" Kisha wailed. Then, at Naomi's gesture, she passed the stick to Sveta.
"My sister wants to have sex with me!" Sveta shouted, then offered the stick back to Naomi.
"Okay." Naomi said. "And how does this situation make you feel?" She again held out the stick for Kisha.
"It makes me feel unloved, unwanted, and pent up!" Kisha said. "I wanna sit on Sveta's face and have her eat me out again! I want to kiss her while we grope each other's boobs!"
"Ew!" Sveta said. "That's not normal!"
Naomi pointed at the stick in Kisha's hand.
Then Kisha grabbed Sveta, flipped her onto her stomach, and pulled down her shorts.
"What are you-" Sveta started, only to be cut off when Kisha smacked her bare ass with the ruler.
"You spoke up twice without the stick." Kisha said, spanking her sister's other asscheek.
"Ahhnn." Sveta whined.
The other two girls stared at her in silence for a moment.
"Say yes if you want to get spanked some more, kitty." Kisha said, sliding her legs out from under Sveta's torso.
Sveta hurriedly shook her head. Both Kisha and Naomi frowned in disappointment.
"I thought we loved each other like sisters and like lovers, but then I come home to a locked door and no response. I buried myself in work to help numb the pain." Kisha finished, then passed the stick to Sveta, her body pinned beneath Kisha's thighs.
"Nope." Sveta said. "I've been... distracting myself... so I don't think about it."
Heavenly Testament reached out for, and recieved, the stick.
"This distraction... it wouldn't have anything to do with the fact all your panties are in the dirty laundry hamper, would it?" Heavenly Testament said, raising an eyebrow.
There was several moments of silence.
"That's... that's not what I was doing!" Sveta shouted. Heavenly Testament leaned forward and spanked Sveta again.
"What did you think I was referring to?" Naomi grinned.
Sveta received the stick, which she was almost as bright red as. "I... uh... er... um... er..."
Kisha clambered onto the back of the couch while her sister stammered, then flipped said sister onto her back before immediately tackling her and shoving her tongue down her throat. Several seconds later, Kisha emerged with the stick.
"Were you touching yourself while thinking of me?" Kisha teased, then passed the stick back along with some more saliva.
"Yesh." Sveta said, slurring.
"Yes what?" Kisha said, holding onto the stick without Sveta releasing it.
"Yes mistress." Sveta said.
"Good kitty." Kisha said, going in for another kiss while stroking her sister's head.
(Yes, this is clearly not attempting to be canon.)
(Fake edit: I see I got a bit ninja'd here.)