Is it okay to group several Components into a single lifeline for simplicity?
For example, let's say I have a UML Component Diagram, and it's a layered architecture. There are 26 components, one on top of the other, component A to Component Z.
The interface to the system is Component A and the processing is in Component Z. When a message is sent to Component A, the messages flows down the Component Stack all the way to Z to be processed, then the result flows back up to A. Now let's say that component N does something interesting with the message that we want to show on our Sequence Diagram, but the other components are purely passing the message to the next component.
Many of these systems are outside my immediate control (3rd party systems, done by other developers, etc). The overall real-time system is more like a system of systems. Because of this, I would like to somehow simplify their representation in my sequence diagram to focus on specific parts of the system.
I could create a Sequence Diagram with 26 lifelines that shows the flow between every component from A to Z and back again, but it seems like it would just clutter the diagram.
Is there a good way to simplify my UML in order to summarize the pieces that I am not interested in? There are a few reasons this might not be important, whether the message of interest never travels through them or other reasons. Or is UML the wrong tool and should I be using something different?