Grouping 3 unique sprites, then randomizing their location?

Hi,

Im in the process of creating a 2d game similar to Columns, but wondering how would be the best way to achieve grouping the actors in a column, then randomizing their position in the column/collision box.

All while they are moving down the screen.

E.g. I have apple, orange, pear in the collision box, upon pressing W it changes the order to orange, pear, apple.