This is obviously not a complete list of the Harry Potter canon characters. Some names you can see below come from fan theories, there is no need to take it seriously. If you want to play a character that is not listed you are more than welcome to do so.

Harry Potter & Ginevra Weasley
m. James Sirius Potter [G, 7]
m. Albus Severus Potter [G, 6]
f. Lily Luna Potter [G, 5]

Bill Weasley & Fleur Delacour
f. Victoire Weasley [ ? ]
? Dominique Weasley [?, 7]
m. Louis Weasley [?, ?]

Oliver Wood & Variannah Harper
f. Madison Wood [?, 7]
f. Kimberly Wood [?, 7]
m. Ryan Wood [?, 5]

George Weasley & Angelina Johnson
m. Fred Weasley [G, 7]
f. Roxanne Weasley [G, 6]

Ronald Weasley & Hermione Granger
f. Rose Weasley [G, 6]
m. Hugo Weasley [G, 5]

Percy Weasley & Audrey Weasley
f. Molly Weasley [?, 7]
f. Lucy Weasley [?, 6]

Rolf Scamander & Luna Lovegood
m. Lorcan Scamander [?, 7]
m. Lysander Scamander [?, 7]

Marcus Flint & Katie Bell
m. Martin Flint [S, 7]
f. Julie Flint [G, 5]

Neville Longbottom & Hannah Abbott
f. Alice Longbottom [?, ?]
f. Amelia Longbottom [?, ?]

Draco Malfoy & Astoria Greengrass
m. Scorpius Hyperion Malfoy [S, 6]

Dennis Creevey & Orla Quirke
m. Colin Creevey [?, ?]

Cassius Warrington & Lavender Brown
f. Lindsay Warrington [?, ?]

Seamus Finnigan & Demelza Robins
m. Arnold Finnigan [?, ? ]
f. Stephenie Finnigan [?, ?]

Ernie Macmillan & Susan Bones
m. Michael Macmillan [?, ?]
m. Robert Macmillan [?, ?]

Michael Corner & Marietta Edgecombe
m. Peter Corner [?, ?]
f. Jane Corner [?, ?]

Cormac McLaggen & Parvati Patil
m. Jason McLaggen [?, ?]

Roger Davies & Cho Chang
m. Henry Davies [?, ?]

Remus Lupin & Nymphadora Tonks
m. Ted "Teddy" Lupin [ ? ]