Can a Protected Simulink Block ever be used to generate rweal-time code in a larger parent model?

Is it possible to re-use a Protected Simulink Block in a larger parent model in R2012b Simulink, and from this to generate generic real-time (s-FUNC) code from it?

Background:

We are having some difficulty re-using a supplier model delivered as a "Protected Simulink Block". This model must be used in a larger model from which generic real-time code (grt.tlc) will be generated to allow re-compilation in another real-time environment. We are doing everything in MATLAB Version R2012b (32-bit) under Windows7 operating system.

I suspect the Protected Simulink block may have been creating in a later version of MATLAB, although to date it does work OK as-is in R2012b (which is a bit of a mystery) provided I don't attempt to generate an S-Function from it.

Our supplier insists the Protect Block has been set up to allow code generation (obfuscated code) but I immediately get a complaint from Simulink that my model contains "Model Blocks" which are only compatible with ert.tlc. Switching to ert.tlc then generates more errors/complaints about the use of Continuous Time (in ert.tlc code) so I am stuck.