What the community has been doing knowing JK Rowling is a transphobe:
When buying merch, fans have been inclined to buy handmade goods or second hand items to prevent money going to the creator.
When buying a ticket to a movie, or play, or renting video material, fans have been offsetting the damage of giving money to the creator by donating to charities that are trans friendly.
Writing to Warner Bros. to appeal to the creator to change her mind.
Writing to the creator directly to try and change her mind (though this has been done for a while, and she’s refusing to see the harm she’s doing).
Fans are taking ownership of the series and referring to the creator as she who should not be named. We can understand that this is not the first children series to have an author who hates kids, in this case she hates trans kids. There is no more vulnerable demographic minority than bipoc trans kids, they are at the highest risk of suicide.
JK Rowling is behind delaying surgeries, preventing hormone therapies, disallowing safe spaces, use of chosen pronouns. She stands behind and supports other known transphobes. She may have had a personal encounter that has shaped her view, but an isolated incident is no excuse to hate an entire group of marginalized people. On top of her hate, she’s letting that emotion fuel further bigotry. Her fellow radical feminist friends are living in an echo chamber.
The final thing you can do is read a variety of books found in the young adults section not written by her. Support perspectives that are varied. There are lists of Harry Potter alternatives. HP inspires children to read. So let them read. But parents and guardians need to make themselves available to have conversations about what is wrong in the series. Point out the series and the author’s failings.
As always, I encourage parents to be familiar with the material before letting their children read and decide if the subject matter is safe. Here is a list of trans inclusive young adult books to read: https://www.queerevents.ca/queer-corner/blog/books/trans-inclusive-alternatives-harry-potter