One way to change the subsystem reference in the MATLAB editor is by using the “set_param” function in this way:
set_param(path_subsys_ref,'ReferencedSubsystem',subsys_var);
where "path_subsys_ref" is the path to Subsystem Reference / name of the Simulink model, and "subsys_var" is the desired Subsystem file name. In this case, the "path_subsys_ref" would be "test_model" and "subsys_var" would be both "product_2" and "product_3".
As an example, here is some code that would help with programmatically changing the Subsystem Reference:
simIn = Simulink.SimulationInput("test_model");
load_system("test_model")
set_param('test_model/Subsystem Reference','ReferencedSubsystem','product_2'); %Select model name, then the block reference
out = sim(simIn);
out.simout.Data
