What's the Name of That Book??? discussion

I believe this book is a YA novel since I read it when I was a teen, about 5 years ago. This is a series, so I might be jumping back and forth between different novels without knowing.
SPOILERS AHEAD: So two sisters move into a new town with their mother, I don't remember if they had a father. The older sister joined a soccer club, while the younger sister had an extensive vocabulary and was considered possibly smart for her age due to that.
After a bit, the younger sister disappears, and the older sister had to solve this mystery on how to find her. I think her mother's memory was erased, since she didn't remember having a younger daughter and this is what tipped the older sister off (I could be wrong, it's been many years since I read it). I remember one scene being where the older sister touches a feather and suddenly remembers her sister (her memory was erased too). She meets a very old woman who had a sister, but who disappeared as well.
Along the way, the sister finds out that the town has magic and witches who take away young kids. She ends up getting her sister back, and the lady's sister as well (who aged to an old age).
Some tidbit scenes I remember: the older sister ends up teaming up with her female classmates who end up casting a love spell on a boy at one point. The younger sister was taken to a place where they were forced to dance constantly (I think). At the end of one of the books, the younger sister is taken away (or offers herself), ages a ton of years, and becomes a witch. This was the latest book in the series, they were gonna make another but I had to wait.

If anyone knows the name, please reply. Thank you!

I believe your book is The Secret of Grimm Hill! A good one for sure, and one I’ve also struggled to track down in the past.

Ember wrote: "I believe your book is The Secret of Grimm Hill! A good one for sure, and one I’ve also struggled to track down in the past."

Yes, that's the book!! Thank you so much for helping me find it!

Glad you found your book, Ivona. Here's the link for Ember's find - The Secret of Grim Hill by Linda DeMeulemeester.