Terminology of a client/module agnostic system where a parent doesn't know existent of child scenario.

I have a system that is self-sufficient/client agnostic and does not know about modules that can be plugged into it, the system has no module code and the modules use an API to extract data from the main system.

What is the technical phrase for a system that doesnt know about or need to know subsequent 'child' modules?

plug and play is not the one Im thinking of.

Im trying to find a way for a module to inherit characteristics/sections of the parent without the parent knowing about the module and then overriding the those it needs/wants with its own if necessary.

For example permissions, I dont want to maintain 2+ permissions matrices for parent and module, however, I dont want the Parent to contain any matrices that the module needs as that implies the parent knows of the module.

Any pointers on the terminology or the design patterns of the above as I have been out of the coding world for 3 years and cant quite remember what I used to call the above.