Anyone wanna try writing this?  I'm good at coming up with ideas but not so much at actually expanding them into screenplays.  Here are my ideas:
-Terabithia is a real place that Jesse and Leslie find by crossing a magical bridge they find in the woods
-Their classmates are instead reimagined as the various talking animal sidekicks or whatever who inhabit Terabithia, and an adult version of Scott Hoager reimagined into a Ganondorf-esque character is the main villain, however the part about Jesse sneaking off to be alone with Miss Edmund still happens in the “real” world
-instead of dying, whatever happens to Leslie when Jesse is away instead leaves her in a state where she’s instead living on borrowed time, similar to what happens to Garl in Sea of Stars, and she will also die of she leaves Terabithia in this state so none of the adults at home know what happened to her and just think she went missing.  After Hoager is defeated (probably because he fell off the bridge and plummeted to his death like 95% of all other Disney Villains do) it appears that they failed to do whatever it is they needed to do to save her life or maybe the situation seemed to be completely hopeless the entire time or whatever but then a miracle happens followed by your standard Disney happy ending sequence
-if you're going to write songs (and I really hope you do) try to make them sound as Alan Menken-ish as possible