codegen will replacing a subfunction with dummy function work?

I am using codegen to convert a Matlab code to C. Part of the code contains quite a few Matlab functions that are not supported by codegen. so my plan is to isolate and delete this part of code in Matlab, then create a dummy function to fill the caused logic hole in the rest of the code. The rest of the code will call this dummy function get the right return type. Later after I convert the rest of the code and also the dummy function to C, then I plan to rewrite the dummy function to implement the intended functionalities.

I have one issue and one question:

the issue is maybe because the dummy function I used is too easy or some other reasons, it is absorbed by the rest of the code. It didn't appear as a separate function in the generated C code folder, which failed my purpose. Does anyone know why this happened? And how can I create a dummy function that can be isolated to a separate function so that I can have a space holder to put in my real code later?

my question or doubt is: does anyone know will this strategy I described above work or not? Is there anything I need to be careful about in order to make it work?

I really appreciate your help!