Request: The combination fragment of a sequence diagram

Hi, I’m using it conveniently.
What I would like to suggest is about the rectangle in The combination fragment of a sequence diagram.
I’m trying to do this by making the shape transparent and using only a frame to represent it, but I can’t click on any object within this range.
If I move this shape, other shapes are also moved.
What I want to do is to make the line segment of the rectangle independent from the other shapes.
This would be useful for drawing the combination fragment of a sequence diagram.