Ability to add files to the template without code changes

I'm using typescript-fetch template to generate TS api client.
In addition to all standard files I want to generate actions and reducers for my redux code.
Correct me if I'm wrong, but the current template does not support any additional files, so I can't simply add a new file e.g. apis.actions.mustache and use it to generate the file in apis folder?

Is that possible to add some sort of references (e.g. partials from mustache) to automatically resolve templates from files?

template/
.. apis.mustache
.. my_custom.mustache

in apis.mustache to add {{> my_custom }} and the file my_custom.mustache will be used to generate this partial with the model which was passed to apis.mustache

Start with the typescript-fetch template and the mentioned template/apis.mustache and my_custom.mustache files. Trace how template files and Mustache partials are resolved, then determine the scope of supporting additional generated files without code changes. Done means a defined, usable mechanism for including custom files and generating them in the apis folder.