添加到现有类的TypeScript类型

我正在尝试为骨干网嵌套模型添加功能到现有骨干网的类型。模型:

/// <reference path="../backbone/backbone.d.ts" />
declare module Backbone {
    class Events {
    }
    class ModelBase extends Events {
    }
    class Model extends ModelBase {
        setRelation(attr, val, options):any;
        set(key, val, options):any;
        toJSON(options):any;
        clone(options):any;
        resetRelations(options):any;
        reset(model,options):any;
    }
}
declare module "backbone-nested-models" {
}

但是它告诉我这些类已经存在了。

我是否被迫将这些函数添加到我的主干类型本身?