Architecture: entity framework Web Api

I'm creating a web api program using entity framework. So as the basis, I have an sql server database which I'm connected to with entity framework trought my web api program. Using an add-on for entity framework, I'v generated classes according to my database tables. However i don't want to use these classes for my webservices because I don't need to display some of the attributes generated by the entity framework and little bit tricky with all the proxies problems. These attributes are especially generated because of the foreign keys. As below, for this generated class, I don't need to display "Societe" object and "Utilisateur" object:

 public partial class FonctionnalitePerUser
{
    public int FonctionUserLngId { get; set; }
    public int FonctionUserLngUserId { get; set; }
    public int FonctionUserLngSocieteId { get; set; }
    public virtual Societe Societe { get; set; }
    public virtual Utilisateur Utilisateur { get; set; }

}

I would need some advice to avoid displaying that entities in my webservices. I was thinking about 3 possibilities:

• As it's a partial class, I might create an other partial class with the same name where I put the attributes that I need and override the constructor.
• I might inherit a custom class from that one to override the constructor in order to get one structured as I need.
• I might create Management classes with functions that create the perfect objects that I need for my webservices. I mean functions that convert "FonctionnalitePerUser" object to "FonctionnalitePerUserCustom" objects.

These are the 3 solutions that I've found. In order to get the best performance, I was wondering if anyone can give me some advise about that or either propose some other solutions. Thanks in advance