Hi, this should help anyone who is unsure anout characters or relevant ages. The characters are all Canon. My guess of ages in the Epilogue. Then some of my guesses for other characters.
As of 1st September 2017
Remus and Tonks Lupin
Teddy Lupin - 19
Bill and Fleur Weasley
Victoire Weasley - 17
Dominique Weasley - 15
Louis Weasley - 14
Percy and Audrey Weasley
Molly Weasley II - 10
Lucy Weasley - 8
George and Angelina Weasley
Fred Weasley II - 14
Roxanne Weasley - 12
Ron and Hermione Weasley
Rose Weasley - 11
Hugo Weasley - 9
Harry and Ginny Potter
James Potter II - 13
Albus Potter - 11
Lily Potter II - 9
Luna and Rolf Scamander
Lorcan Scamander - 9
Lysander Scamander - 9
Draco and Astoria Malfoy
Scorpius Malfoy - 11
And these are ones I have made up
Neville and Hannah Longbottom
Frank Longbottom II - 13
Alice Longbottom II - 10
Francine Longbottom - 8