Where did あなた heard this?

In the epilogue it was 発言しました that Harry and Ginny are merried and they have 3 kids: Albus,Lily and James,that Ron and Hermione are merried and they have 2 kids: Rose and Hugo,and that Draco has son named Scorpious.It's also mentioned that Neville is working in Hogwarts as Herbology teacher and that Tonks's and Lupin's son Tedd is a boyfriend to Victoire,Bill's and Fleur's daughter.But were was 発言しました what happend to Luna,other Weasleys,where do Harry,Hermione,Ron and Ginny work,and what are the middle names Lily Jr. and James Jr.I mean,I read a book at least 10 times and I haven't seen these stuff there.But when I was online I saw that Percey has merried Audrey and they have daughters Molly and Lucy,that George merried Angelina and they have kids named フレッド and Roxanne,that Bill and Fleur have 2 kids もっと見る named Dominique and Louis and so forth.I also read that Hermione is working at Ministry of magic,that Ginny became a Quidich player,that Neville merried Hannah Abott,that Lily's middle name is Luna and Jame's is Sirius...So I was wondering did あなた heard about what happend to the other characters?Is it just a fanfiction that became 人気 または did J.K Rowling realy wrote it on her website または in some short book maybe?I'm just asking this cause I'm huge HP ファン since I was 4 years old and this is the only thing I don't understand about it.