How to create a group of methods/properties within a class?

I am using entity framework with a web service and I have entity partial class objects that were generated automatically by the web service.

I would like to extend these classes, but I would like to group them in the generated class in a way similar to the way a namespace would (except inside a class).

Here is my generated class:

public partial class Employee : Entity
{
   public int ID { get; set; }
   public string FirstName { get; set; }
   public string LastName { get; set; }
}

And I want to add some new properties, functions, etc similar to:

pu开发者_JAVA技巧blic partial class Employee : Entity
{
   public string FullName {
      get { return this.FirstName + " " + this.LastName; }
   }
}

However, I would like to group any additional properties together so I have a little more visible separation from the generated methods. I would like to be able to call something like:

myEmployee.CustomMethods.FullName

I could create another class within the partial class called CustomMethods and pass a reference to the base class so I can access the generated properties. Or maybe just name them a particular way. But, I am not sure what is the best solution. I am looking for community ideas that are clean and fall under good practice. Thanks.

Here is another solution using explicit interfaces:

public interface ICustomMethods {
    string FullName {get;}
}

public partial class Employee: Entity, ICustomMethods {
    public ICustomMethods CustomMethods {
       get {return (ICustomMethods)this;}
    }
    //explicitly implemented
    string ICustomMethods.FullName {
       get { return this.FirstName + " " + this.LastName; }
    }
}

Usage:

string fullName;
fullName = employee.FullName; //Compiler error    
fullName = employee.CustomMethods.FullName; //OK

public class CustomMethods
{
    Employee _employee;
    public CustomMethods(Employee employee)
    {
        _employee = employee;
    }

    public string FullName 
    {
        get 
        {
            return string.Format("{0} {1}", 
                _employee.FirstName, _employee.LastName); 
        }
    }
}

public partial class Employee : Entity
{
    CustomMethods _customMethods;
    public CustomMethods CustomMethods
    {
        get 
        {
            if (_customMethods == null)
                _customMethods = new CustomMethods(this);
            return _customMethods;
        }
    }
}

typically I would put Properties like FullName right on the Partial class but I can see why you might want separation.