Yeah, it definately is a bad tool for working with multiple drawings, but I always find myself needing to do this.
I have at least narrowed down the problem. While all other variables carry over from the first drawing to the second, the selection set (ss1 in my program) does not. AutoLISP loses the selection set.
This is crucial to my program because it uses while-loops to compare all of the entities in the two selection sets. The only work-around I can think of is to extract all the necessary information from each entity in the first selection set before the second drawing is opened, and save this information to a variable or a list, and then compare those variables or lists to the entities from the second selection set (in the second drawing).
This, however, would be very complex, and it would be really nice if my first selection set just carried over to the second drawing. Se la vi 🙂
Thank you anyway for taking a look.