diff --git a/app/models/metadata_belongs_to.rb b/app/models/metadata_belongs_to.rb
index b94fbc2..2119547 100644
--- a/app/models/metadata_belongs_to.rb
+++ b/app/models/metadata_belongs_to.rb
@@ -73,6 +73,14 @@ class MetadataBelongsTo < MetadataRelatedPosts
     @belonged_to ||= posts.find(document.data[name.to_s], uuid: true)
   end
 
+  def related_posts?
+    true
+  end
+
+  def related_methods
+    @related_methods ||= %i[belongs_to belonged_to].freeze
+  end
+
   private
 
   def sanitize(uuid)
diff --git a/app/models/metadata_has_many.rb b/app/models/metadata_has_many.rb
new file mode 100644
index 0000000..03eb986
--- /dev/null
+++ b/app/models/metadata_has_many.rb
@@ -0,0 +1,71 @@
+# frozen_string_literal: true
+
+# La diferencia con MetadataRelatedPosts es que la relación también
+# actualiza los Posts remotos.
+#
+# Localmente tenemos un Array de UUIDs.  Remotamente tenemos una String
+# apuntando a un Post, que se mantiene actualizado como el actual.
+class MetadataHasMany < MetadataRelatedPosts
+  # Todos los Post relacionados según la relación remota
+  def has_many_remote
+    @has_many_remote ||= posts.where(inverse => post.uuid.value)
+  end
+
+  # Todos los Post relacionados
+  def has_many
+    @has_many ||= {}
+    @has_many[value.hash.to_s] ||= posts.where(uuid: value)
+  end
+
+  # La relación anterior
+  def had_many
+    return [] if document.data[name.to_s].blank?
+
+    @had_many ||= posts.where(uuid: document.data[name.to_s])
+  end
+
+  def inverse?
+    inverse.present?
+  end
+
+  # La relación inversa
+  #
+  # @return [Nil,Symbol]
+  def inverse
+    layout.metadata.dig(name, 'inverse')&.to_sym
+  end
+
+  # Actualizar las relaciones inversas.  Hay que buscar la diferencia
+  # entre had y has_many.
+  def save
+    self[:value] = sanitize value
+
+    return true unless inverse?
+
+    (had_many - has_many).each do |remove|
+      remove[inverse].value = remove[inverse].default_value
+    end
+
+    (has_many - had_many).each do |add|
+      add[inverse].value = post.uuid.value
+    end
+
+    true
+  end
+
+  def related_posts?
+    true
+  end
+
+  def related_methods
+    @related_methods ||= %i[has_many had_many].freeze
+  end
+
+  private
+
+  def sanitize(sanitizable)
+    sanitizable.map do |uuid|
+      uuid.gsub(/[^a-f0-9\-]/, '')
+    end
+  end
+end
diff --git a/app/models/metadata_template.rb b/app/models/metadata_template.rb
index 80c99e4..6242f8f 100644
--- a/app/models/metadata_template.rb
+++ b/app/models/metadata_template.rb
@@ -10,14 +10,6 @@ MetadataTemplate = Struct.new(:site, :document, :name, :label, :type,
                               :layout, keyword_init: true) do
   include ActionText::ContentHelper
 
-  # Métodos que tienen artículos relacionados
-  #
-  # Ver el final del archivo.
-  #
-  # XXX: Por alguna razón no se pueden definir constantes en un Struct
-  #
-  # RELATED_METHODS = %i[]
-
   # El valor por defecto
   def default_value
     raise NotImplementedError
@@ -85,6 +77,14 @@ MetadataTemplate = Struct.new(:site, :document, :name, :label, :type,
     true
   end
 
+  def related_posts?
+    false
+  end
+
+  def related_methods
+    raise NotImplementedError
+  end
+
   private
 
   # Si es obligatorio no puede estar vacío
@@ -106,6 +106,3 @@ MetadataTemplate = Struct.new(:site, :document, :name, :label, :type,
   end
 end
 # rubocop:enable Metrics/BlockLength
-
-# Definir la constante después de definir el Struct.
-MetadataTemplate.const_set 'RELATED_METHODS', %i[belongs_to belonged_to].freeze
diff --git a/app/services/post_service.rb b/app/services/post_service.rb
index d847a9d..46e7a64 100644
--- a/app/services/post_service.rb
+++ b/app/services/post_service.rb
@@ -118,7 +118,9 @@ PostService = Struct.new(:site, :usuarie, :post, :params, keyword_init: true) do
     files = [post.path.absolute]
 
     post.attributes.each do |a|
-      MetadataTemplate::RELATED_METHODS.each do |m|
+      next unless post[a].related_posts?
+
+      post[a].related_methods.each do |m|
         next unless post[a].respond_to? m
 
         # La respuesta puede ser una PostRelation también
diff --git a/app/views/posts/attribute_ro/_has_many.haml b/app/views/posts/attribute_ro/_has_many.haml
new file mode 100644
index 0000000..d6b51a7
--- /dev/null
+++ b/app/views/posts/attribute_ro/_has_many.haml
@@ -0,0 +1,6 @@
+%tr{ id: attribute }
+  %th= post_label_t(attribute, post: post)
+  %td
+    %ul{ dir: dir, lang: locale }
+      - metadata.has_many.each do |p|
+        %li= link_to p.title.value, site_post_path(site, p.id)
diff --git a/app/views/posts/attributes/_has_many.haml b/app/views/posts/attributes/_has_many.haml
new file mode 100644
index 0000000..13439fa
--- /dev/null
+++ b/app/views/posts/attributes/_has_many.haml
@@ -0,0 +1,22 @@
+.form-group
+  = label_tag "post_#{attribute}", post_label_t(attribute, post: post)
+
+  .mapable{ dir: dir, lang: locale,
+    data: { values: metadata.value.to_json,
+    'default-values': metadata.values.to_json,
+    name: "post[#{attribute}][]", list: id_for_datalist(attribute),
+    remove: 'false', legend: post_label_t(attribute, post: post),
+    button: t('posts.attributes.add'),
+    described: id_for_help(attribute) } }
+
+    = text_field(*field_name_for('post', attribute, '[]'),
+      value: metadata.value.join(', '),
+      dir: dir, lang: locale,
+      **field_options(attribute, metadata))
+
+  = render 'posts/attribute_feedback',
+    post: post, attribute: attribute, metadata: metadata
+
+  %datalist{ id: id_for_datalist(attribute) }
+    - metadata.values.keys.each do |value|
+      %option{ value: value }