Starting with version 1.5 of ProB, how the parser resolves referenced can be customized.
By default ProB will try to find files referenced from a machine (using SEES, INCLUDES, DEFINITON-files, etc) resolving paths as relative to the current machine or within the ProB standard library.
Commonly used files can be placed in a shared location, e.g. in the standard library (the stdlib directory in the ProB distribution) or any custom location.
The search path can be customized by defining a PROBPATH environment variable that contains a “:” separated list of directories to be searched, e.g.:
PROBPATH=~/myproject/common:~/myotherproject/common probcli model.mch
will resolved referenced files relative to model.mch, then in ~/myproject/common then in ~/myotherproject/common and finally in the standard library of ProB, stopping as soon as a file with the name being looked up is found.