Rails4 / has_many through / accepts_nested_attributes_for / allow_destroy / nested form
Models:
class Car < ActiveRecord::Base
has_many :garages
has_many :houses, through: :garages
accepts_nested_attributes_for :garages, allow_destroy: true
end
class Garage < ActiveRecord::Base
belongs_to :car
belongs_to :house
accepts_nested_attributes_for :house
end
class House < ActiveRecord::Base
has_many :garages
has_many :cars, through: :garages
end
Nested form here: