Make SoundClass Inheritable?

Hi,
Right now I get thrown a bunch of linker errors in a class inherited from SoundClass. After exploring some problems other people were facing, I realized that it is probably because of the lack of the ENGINE_API macro before the SoundClass declaration.

I actually wanted to add an Enum to uniquely identify my SoundClasses (UI sound, Sfx, background music etc.) inside C++. If there is an alternate way to do it, then I would be more than happy of someone lets me know. If not, then I request the Epic people to make SoundClass class inheritable so that I can work with it using my custom variables as well.

Thanks