can i do this but not with checkbox?
I have a form to upload 6 pictures example
Thumb
pic1
pic1 big
pic2
pic2 big etc.....
i only require the thumb pic1 and pic1 big until here im ok but i want that if the user uploads a pic2 that pic2 big becomes required if he doesnt select any file for pic 2 then theres no need for pic2 big, any help if this can be done?