Let me know if this is even possible:
Let’s say I do have Director as a parent page and Film as a children page.
Then I need third page with just two selects on it:
First field should display all available Directors. This is easy.
Then second field “Films” should display all films that are childrens for previously selected Director.
So it is like a live select update that depends on previous select. Can I pass a variable of my previous selection to query?
No, this won’t work in the query, or only after you save the value of the director select field.
It can somehow be achieved with custom fields, there is a thread somewhere here on the forum.