Jquery how to animate a div ONLY if at a certain position?

hope your all well... Is there a way to animate a div (slide down) for example if its ONLY at a certain position on the page?
For example, there are four Divs that all have the same class .ALLCONTENT but when a button is clicked (.BUTTONS) only the Div thats at 30px from the top will animate downwards, the rest will remain in the same place.

Basically, slide down a div to a certain position, if that divs in that position already it wont slide further down (the problem im having now with

$(".BUTTONS").click(function(){
     $(".ALLCONTENT").animate({"top":"+=558px"}, 250, 'linear');
     });
 

Thanks, Tom

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