I still can't get it to work. I thought I could change the direction platform behavior objects fell and that would make lining up/setting the cards easier, but I couldn't find how.
Using instance variables didn't really make it work. I tried using frame tags too. I am not sure how R0J0hound recommended. The problem right now is that I can't figuere out how to make it so that cards that have the same variable/frametag/are-in-same-animation-and-frame to interact the way I need them to without interacting with every version of that object.
In general it is to do with picking, you narrow the picked instances with a condition such as 'on object clicked' or 'variable=n', otherwise it picks all instances. In terms of merging, because it is difficult to pick card vs card that's why the suggestion comes above from Rojo about using card vs family to specify object A against object B.