Eloquent’s push() saves the model and its relationships, but first you have to tell what you want to be involved in the relationsship.
Since your user-model/table holds the id of the dealership, I assume that a user can belong to only one dealership, so the relationship should look like this:
User Model:
public function dealership()
{
return $this->belongsTo('Dealership');
}
Dealership Model:
public function users()
{
return $this->hasMany('User');
}
To save a User from the Dealership perspective, you do this:
$dealership->users()->save($user);
To associate a dealership with a user, you do this:
$user->dealership()->associate($dealership);
$user->save();