*Sarah starts an Ask blog.
Sarah: "Okay, so, uh... Hi everyone!  It's me... Uhh.."
Frisk: "Sarah, what are you doing?"
Sarah: "... Uhh...  I thought people might wanna know more about us, so I started an ask blog..."
*Sarah starts to sweat nervously, remembering she didn't tell Frisk about this.
Frisk: "Oh!  Well, did you get any questions yet?"
Sarah: "Moooooom, I just started!  Of course I didn't."
Frisk: "Oh, right... Well, let me know if you need anything."
Sarah: "Okay..!"
*Frisk walks away.
Sarah: "So yeah, I saw some others doing this and I wanted to try for myself!  Feel free to ask any questions for me or my friends, and we'll answer!
Ask anything you want!  Here is a list of the main characters and their parents:
Sarah and Twilight (Flowe) are Frisk's and Asriel's children.  (Both Flowe and Twilight exist in this.)  Blade is Chara's son... Don't ask...
Frisk, of course, is Frisk... But she takes the place of Toriel in this, and Asriel takes Asgore.
Myra is Napstablook and Shyren's daughter, and takes the place of Napstablook. (A sibling to take the place of Shyren is coming soon.) (Yes, I consider her a main character... Don't ask.)
Soren is Sans's and Toriel's only son and takes the place of Sans.  His cousin, Zephyr, is Mettaton's and Papyrus's son, and Forte's brother.  He takes the place of Papyrus; Forte takes the place of Mettaton, though she's more shy. (Credit to Audrey [Live_learn_love_ ] for those two characters.
Spear and Momo are Undyne's and Alphys's daughters. Spear takes Undyne's place, and Momo (one again, credit to Audrey) takes Alphys's place.
Junior is MK's adopted daughter and takes his place.
Bob... Takes Temmie's place. He's her and the annoying dog's... MULTIPLE sons. (Why do I consider this a main character)
So yeah! Ask away! :3