Boy and girl transported to magical land, where they have to defend a castle at some stage

[Grace]

So two books released around 2006-2007 in Australia, a boy and girl (I think they were just friends, not related) were somehow transported to a medieval fantasy land, where I’m pretty sure she ended up being a princess or something like that

I owned the books and lent them to someone I knew in grade four and never got them back :(

[Kris]

Grace, I moved your second request to the "Unsolved" folder because you're looking for a specific book.

Tips for posting a book request -- https://www.goodreads.com/topic/show/...

[Michele]

Grace, are you still looking for this?

[Peter]

The Unicorn Window by Lynette Muir?

[Michele]

The Unicorn Window for the click.

[Will]

Could it be Warriors of Alavna ? Did the boy become a warrior known as a bearsark?