This will definitely make tracking library changes much easier. I like the implementation but think Simulink has some options that will maintain more backwards compatibility. Have you looked at converting the Body Elements, Constraints, etc into referenced subsystems? This method will pull the Body Elements content directly from a different .slx file, instead of having the block open the file directly. I experimented with it a little bit and it may not require rebuilding all old models.

@akeeste Thanks for reviewing this PR and looking into other options. The referenced subsystem is an interesting feature, but unfortunately it does not appear to be compatible with Simulink Library files. If you'd like to take a look I've implemented your suggested revision on my fork here: https://github.com/kmruehl/WEC-Sim/tree/feature_referencedsubsystem. The examples run (with backwards compatibility), but the WEC-Sim Library subsystems do not show up in the Simulink Library.

Top Level:

Body Elements:

I also tried converting the individual subsystem files to library files so that they show up in the Simulink Library, but this broke the referenced subsystems, and I get the following errors:

I'll pay around a bit more, but referenced subsystems don't seem to be the solution for the library. The good news is that referenced subsystems are a great solution for some of our other linked library blocks (e.g. between flex body and rigid body)

UPDATE: @akeeste disregard the issue with the Simulink Library not showing up. I restarted MATLAB and this error went away. I guess I was just messing with the library files too much! I'm running tests now, but it looks like the referenced subsystems will work for the library, and I'll update the linked library blocks this way as well (e.g. between flex body and rigid body). Since the updates on on a different branch I'm going to close this PR and will re-open a new one.