How to Check if a CSYS is used for assembly constraint

I have a pattern of CSYS, and each CSYS is supposed to have specifica component based on a criteria.

I am thinking of (step1)running a check if each CSYS of each instance of the pattern is used as a component constraint reference, (step2)if not then add the component.

I was able to figure out step2, can you please help me with code for step1 or suggest if there is another better approach ?