Adding a block to an array of blocks

[mikeyman]

Here's the concept.

 

I have a large array of the same block with holes in the array and varying edges along the perimeter. Depending on the drawing this block changes size in both dimensions.

 

How can I have CAD add a separate block to any block in the array that does not have one to its right. (or add an attribute to the right edge block to eventually populate a table with the quantity of blocks with none to its right).

 

I have no clue how to begin this.