Twilight called an emergency meeting with all the mane 6. She also invited the pillars, as they were in the neighbourhood.
"So you mean to tell me there are two sirens in ponyville?" said Starswirl
"Yes, I quadruple checked to make sure." said Twilight
"So, what are we going to do?" asked fluttershy.
"Unfortunately, we can't banish them. According to twilight, the realm that the original three sirens were banished to has magic now..." said Flash Magnus.
"So what are our next steps?" asked Rarity.
"I propose that we go over to them and try to figure out their intentions. We try to resolve this as peacefully as possible. I don't want ponyville to be reduced to rubble... again" Said twilight.
With that in mind, they decided that only the mane 6 should approach the sirens, as they had met them before. They set off to the Sweet tooth shoppe.
"Hello Pinkie!" said Sweet Melody
"Hey sweet melody! Is your grandma around?" asked Pinkie
"Yup. Why do you ask?" asked Sweet Melody
"Oh, we just wanted to talk to the both of you." said Applejack.
"Sweet Melody! Who are you talking to!" yelled Sour requiem
"Just the elements of harmony. They wanted to talk with us!" said Sweet Melody.
Sour Requiem emerged from the kitchen.
"Talk about what?" she said
"Oh nothing... except that we know that you two are SIRENS!" said Rainbow Dash
Sweet Melody looked absolutely flabbergasted. Sour Requiem simply said "Hm... You're all smarter than you look."
"H-H-How did you guys find out?" asked Sweet Melody
"Let's not talk about how we know. Instead, let's talk about what we're going to do know." said Twilight
"Whatever do you mean princess?" said Sour Requiem
"I just want to know, why are you two here in Ponyville? What are your intentions?" asked Twilight
"That's for me to know and you to never find out" said Sour Requiem.
"Listen, lady! You'd better tell Twilight what she wants to know, or else..." began Rainbow dash
"Or else what? Your merry band of misfits will tear us limb from limb? That doesn't seem very friendly now, does it?" sneered Sour Requiem.
"Listen, Sour Requiem, I don't want this to turn into another siren incident." said Twilight.
"When have you met other sirens" asked Sour Requiem
"That's a funny story! A looong time ago, Starswirl and the pillars banished three sirens to another world that didn't have magic, but then thanks to sunset shimmer it did have magic, so the sirens tried to take over the world so twilight and her human realm friends teamed up to defeat them and they ran away." said Pinkie pie, all without stopping to breath.
"Wait, wait, wait. Three sirens?" asked Sour Requiem.
"Yes" said Twilight, slightly confused.
"And their names were adagio dazzle, aria blaze and sonata dusk?" asked Sour Requiem
"How did you know that?" asked Twilight
"Do you have a way of contacting this other world?" asked Sour Requiem.
"Yes. And why are you ignoring my questions?" said Twilight
"I need you to get a message to the dazzlings." said Sour Requiem
"What?" asked Twilight
"Tell them to get over here as soon as possible. And tell them that Sour Requiem asked for them." said Sour Requiem.
"Why?" asked Twilight
"Once they get here, I'll be happy to answer any questions you all may have." said Sour Requiem.
"OK..." said Twilight. she then teleported the book into the room and wrote a message to sunset shimmer.
In the human world
Of all the people the dazzlings expected to knock on their door, sunset shimmer was not one of them.
"What do you want, shimmer?" asked Adagio
"I got an urgent message from princess Twilight-" began Sunset
"Not interested" said adagio as she began to close the door.
"WAIT! she said you have to return to equestria immediately!" said Sunset
"Still not interested" said Adagio
"She also said that someone called Sour Requiem wanted to see you." said Sunset
That gave Adagio pause.
"What did you just say?" asked Adagio
"That Sour Requiem wanted to see you?" said Sunset
"DID SHE SAY SOUR REQUIEM!" said Sonata
"Stop shouting sonata! But seriously did she say Sour Requiem?" said Aria
"Yes..." said Sunset.
"That's impossible." said Aria
"Obviously it's not!" snapped Adagio
"Who is Sour Requiem anyway?" asked Sunset.
"She's our little sister." said Sonata