I recently had a message from a user on SyncroSim 2.2 that could not open an stsim SyncroSim library and received an error message stating that the library could not be opened because the package stsimdmult was missing. To resolve this issue:
1. Download the stsimdmult package from: https://github.com/ApexRMS/stsimdmult/releases/download/3.2.5/stsimdmult-3-2-5.ssimpkg and save the file locally
2. Open SyncroSim 2.2 and select File | Packages | Install From File… (on the upper right corner of the packages window)
3. Navigate to the file you downloaded in #1 and select Open
4. You should now be able to open your library
We are no longer supporting the stsimdmult package because you can use the more general External Program feature in ST-Sim to acomplish what was done by this package. My recommendation is that you remove stsimdmult from your libraries in version 2.2 of SyncroSim by navigating to File | Library Properties | Add-ons and unchecking the box for stsimdmult. Eventually when none of your libraries depend on this package you can remove it from SyncroSim under File | Packages | Remove