Question About Block Replacement

Say there is a line of a random assortment of four different blocks (Blocks 1, 2, 3, 4) that, when activated, can become Blocks 1a, 2a, 3a, and 4a.

How do I make it so that when I right-click the first block in the line, the entire line doesn't activate at once, but instead the blocks activate in a domino effect?