How to extend the functionality of the library?

Question

typescript

There is a library with the following structure:

declare class LibName extends events.EventEmitter { }

declare namespace LibName {
...
class Server extends events.EventEmitter {}
...
}

export = LibName

How can it be expanded, while transferring all the functionality of namespaces?
I need to expand exactly LibName by adding a public value to it, and at the same time extend the Server functionality from neipspaces.
Dropped something like this:

import * as LibName from "libname";

class CustomLibName extends LibName {}
namespace CustomLibName {
    export class Server extends LibName.Server {}
}

export = CustomLibName

But if I add a parameter to the class CustomLibName and try to access it through the class Server, then I get an error that it is not visible. How to be? In the library itself, Server somehow sees other parameters from LibName.