I for one won't be watching this terf sponsored trash.

Use all the subplots: Marauders' story, Collin Creevey, Quidditch trainings etc

I'd love to see just some stuff that got missed because there was likely no time to fit them in.

things like the Sphinx would have been cool to see. I always wondered what it would look/sound like.

They could cut out all the racist names, random bigotry, and not give any money to be used of anti-LGBTQ non-profits.

I think that's the best thing they can do for the franchise

What foreshadowing can they do or add scenes that the movie didn't know would be relevant?

Definitely Sirius giving Harry the magic mirror in OotP. The movies cut this but included the mirror shard in DH with no explanation.

The movies kind of relegated Ginny to a background character for PoA through OotP, and only gave her screen time once she became a love interest for Harry in HBP. The series should include more of Ginny's scenes between CoS and HBP, such as:

• CoS: Ginny sending Harry a Valentine
• PoA: She is present during the dementor attack on the train, and looks "almost as bad as Harry felt"
• PoA: She gives Harry get-well card
• GoF: Ginny comforting Ron after he asks Fleur to the Yule Ball, then being miserable upon realizing that she could have gone with Harry instead of Neville.
• OotP: She is the one who intoduces Luna, not Hermione
• OotP: She reassures Harry that he is not possessed, after the attack on Arthur.

For flashbacks etc before people start aging?

Are there any flashbacks in the books which include the kids? None spring to mind...