Destroy Instances Directly on other instances

Hello ,

I'm working on a grid-based game

and sometimes , I create some instances directly on others ...

I would like to delete instances DIRECTLY at the bottom , let's take an example

I have an instance (1) and I create another instance ontop of the other one (2)

(2) is deletable when

(1)X and Y = (2)X and Y

and not otherwise

But I may have other instances scattered on the screen

so I need to pick (1) -Bottom Instance- and delete it even if there's a third or four instance , taking note of the rule above

How would I go about picking 1 and other instances that follow the rule ?

Thanks for reading and have a nice day

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