Combine Sequence/Communication diagrams?

Is it possible to merge/combine sequence diagrams?
If I have Class1 & Class2, and have 2 sequence diagrams each containing both classes and one interaction between the classes, is it possible for me to see a combined view showing the two classes with both the interactions shown? I’ve tried Communication diagrams but these just show the interaction from one sequence diagram.

See attached file for what I mean.

I’ve used Classes to represent different computer hardware; maybe there is a better way of doing this. I want to develop many sequence diagrams independently using the same Classes (actually they are really different computer hardware), then show a combined list of all messages passing between the computers.
i.e. I need some output (sequence or communication, or any type of output) containing Computer1, Computer2 and a complete list of all messages passing between them, based on several sequence diagrams.

This combined list could be in any format; exported PDF/Excel etc; it doesn’t have to be on a diagram.

Thanks in advance for any advice or alternative ways to do what I want.

Regards Martin Wilkinson