Can I add a common function to a set of EntitySet<TEntity> Classes - LINQ to SQL

I am using LINQ to SQL

and want to add functions to autogenerated EntitySet< TEntity > collections.

eg.

City.Houses

where Houses is automatically generated EntitySet < House >

I am using extension method to add extract function to the EntitySet < House > class

so that I can get something like

City.House.FindByID(id);

but now I also have

City.Bunglows.FindByID(id);

now FindByID basically does the same thing for both these classes.

Will I have to extend Bunglows also and implement the same function again. Can't I do some kind of inhertiance on the autogenerated EntitySet< TEntity > classes??

Commenting on Andrew Hare's answer

But that will make FindByID() available on all EntitySet< TEntity > classes. What if I want to implement that function on these 2 particular entity sets only???

Make your extension method generic like this:

public static TEntity FindByID<TEntity>
    (this EntitySet<TEntity> source, Int32 id)
{
    // ...
}

This will allow you to use this extension method on any closed constructed instance of EntitySet<TEntity> (i.e. EntitySet<House> or EntitySet<Bungalow>) as long as your implementation of FindByID can be appropriately expressed generically.