let's see if I understand correctly

After doing several tests I think I have figured out that they can not create two different sized card in the same stack, at least I did not succeed, right?
Wanting to open a second card of different size from the main card at run time I must create in a different stack to be included in the program and called for this purpose, right?
Admitting that he is right, but I'm wrong, can you give me some more precise indication about?
Thank you.