How to insert a table but the relationship

[eluser]yoelrodguez[/eluser]
Hi I have the following query I made ​​with DataMapper but I want more add a table which has the following relationship one-to-many (Bloque and tema ) the query that I have is as follows:

Controller

$curso = new Curso();
$curso->include_related('Tema','id');
$curso->include_related('nivel','id');
$curso->include_related('usuario','id');
$curso->where('id', $id)->get();

If I try to insert the block model tells me it has no relation with curso

Example:

$curso->include_related('Bloque','id');

Thanks