diff --git a/app/controllers/posts_controller.rb b/app/controllers/posts_controller.rb
index 28295793..bf030ee7 100644
--- a/app/controllers/posts_controller.rb
+++ b/app/controllers/posts_controller.rb
@@ -126,7 +126,7 @@ class PostsController < ApplicationController
         @uuid = @post.uuid.value
         @name = params.require(:name)
 
-        render 'posts/new_has_many_value', layout: false
+        render "posts/#{params.require(:attribute)}_value", layout: false
       else
         headers['HX-Retarget'] = "##{params.require(:form)}"
         headers['HX-Reswap'] = 'outerHTML'
diff --git a/app/models/metadata_new_belongs_to.rb b/app/models/metadata_new_belongs_to.rb
new file mode 100644
index 00000000..db90cb8f
--- /dev/null
+++ b/app/models/metadata_new_belongs_to.rb
@@ -0,0 +1,4 @@
+# frozen_string_literal: true
+
+# Nueva interfaz
+class MetadataNewBelongsTo < MetadataBelongsTo; end
diff --git a/app/views/bootstrap/_custom_checkbox.haml b/app/views/bootstrap/_custom_checkbox.haml
index c8cd1b41..ae35caf5 100644
--- a/app/views/bootstrap/_custom_checkbox.haml
+++ b/app/views/bootstrap/_custom_checkbox.haml
@@ -3,7 +3,7 @@
   checkbox_attributes = local_assigns.slice(:id, :type, :name, :value, :required, :checked)
   checkbox_attributes[:type] ||= 'checkbox'
 
-.custom-control.custom-checkbox
+.custom-control{ class: "custom-#{checkbox_attributes[:type]}" }
   %input.custom-control-input{ **checkbox_attributes }
   %label.custom-control-label{ for: id, aria: { describedby: help_id } }= content
   - if (block = yield).present?
diff --git a/app/views/posts/_htmx_form.haml b/app/views/posts/_htmx_form.haml
index a288aa55..03e82e32 100644
--- a/app/views/posts/_htmx_form.haml
+++ b/app/views/posts/_htmx_form.haml
@@ -58,6 +58,7 @@
   %input{ type: 'hidden', name: 'form', value: options[:id] }
   %input{ type: 'hidden', name: 'dir', value: dir }
   %input{ type: 'hidden', name: 'locale', value: locale }
+  %input{ type: 'hidden', name: 'attribute', value: params.require(:attribute) }
   %input{ type: 'hidden', name: 'target', value: params.require(:target) }
   %input{ type: 'hidden', name: 'swap', value: params.require(:swap) }
   - if params[:inverse].present?
diff --git a/app/views/posts/attribute_ro/_new_belongs_to.haml b/app/views/posts/attribute_ro/_new_belongs_to.haml
new file mode 100644
index 00000000..c7e06be8
--- /dev/null
+++ b/app/views/posts/attribute_ro/_new_belongs_to.haml
@@ -0,0 +1,6 @@
+%tr{ id: attribute }
+  %th= post_label_t(attribute, post: post)
+  %td{ dir: dir, lang: locale }
+    - p = metadata.belongs_to
+    - if p
+      = link_to p.title.value, site_post_path(site, p.id)
diff --git a/app/views/posts/attributes/_new_belongs_to.haml b/app/views/posts/attributes/_new_belongs_to.haml
new file mode 100644
index 00000000..d30d22dd
--- /dev/null
+++ b/app/views/posts/attributes/_new_belongs_to.haml
@@ -0,0 +1,100 @@
+-#
+  Genera un listado de radios entre los que se puede elegir solo uno para
+  guardar.  Podemos elegir entre los artículos ya cargados o agregar uno
+  nuevo.
+
+  Al agregar uno nuevo, se abre un segundo modal que carga el formulario
+  correspondiente vía HTMX. El formulario tiene que cargarse por fuera
+  del formulario principal porque no se pueden anidar.
+
+:ruby
+  id = id_for(base, attribute)
+  name = "#{base}[#{attribute}]"
+  form_id = "form-#{Nanoid.generate}"
+  modal_id = "modal-#{Nanoid.generate}"
+  post_id = "post-#{Nanoid.generate}"
+  post_form_id = "post-form-#{Nanoid.generate}"
+  post_modal_id = "post-modal-#{Nanoid.generate}"
+  post_form_loaded_id = "post-loaded-#{Nanoid.generate}"
+  value_list_id = "#{id}_body"
+
+%div{ id: modal_id, data: { controller: 'modal array', 'array-original-value': metadata.value.to_json, 'array-new-array-value': site_posts_new_related_post_path(site) } }
+  .form-group
+    = hidden_field_tag name, ''
+    = label_tag id, post_label_t(attribute, post: post)
+    -# Mostramos la lista de valores actuales.
+
+      Al aceptar el modal, se vacía el listado y se completa en base a
+      renderizaciones con HTMX. Para poder hacer eso, tenemos que poder
+      acceder a todos los items dentro del modal (como array.item) y
+      enviar el valor al endpoint que devuelve uno por uno. Esto lo
+      tenemos disponible en Stimulus, pero queremos usar HTMX o técnica
+      similar para poder renderizar del lado del servidor.
+
+      Para poder cancelar, mantenemos el estado original y desactivamos
+      o activamos los ítemes según estén incluidos en esa lista o no.
+    .row.row-cols-3.row-cols-md-4{ data: { target: 'array.current' } }
+      - metadata.values.slice(*metadata.value).each do |value|
+        = render 'posts/new_array_value', value: value
+
+    = render 'bootstrap/btn', content: t('.edit'), action: 'modal#show'
+
+  = render 'bootstrap/modal', id: id, modal_content_attributes: { class: 'h-100' }, hide_actions: ['array#cancel'] do
+    - content_for :"#{id}_header" do
+      .form-group.flex-grow-1.mb-0
+        = label_tag id, post_label_t(attribute, post: post)
+        %input.form-control{ data: { target: 'array.search', action: 'input->array#search' }, type: 'search', placeholder: t('.filter') }
+
+    - content_for :"#{id}_body" do
+      .form-group.mb-0{ id: value_list_id }
+        - metadata.values.each_pair do |value, uuid|
+          .mb-2{ data: { target: 'array.item', 'searchable-value': value.remove_diacritics.downcase, value: uuid } }
+            = render 'bootstrap/custom_checkbox', name: name, id: "value-#{Nanoid.generate}", value: uuid, checked: metadata.value.include?(uuid), content: value, type: 'radio'
+
+    -#
+      Según la definición del campo, si hay un filtro, tenemos que poder
+      elegir qué tipo de esquema queremos o si hay uno solo, siempre
+      vamos a enviar ese. Si no hay ninguno, tendríamos que poder elegir
+      entre todos los esquemas.
+
+    - content_for :"#{id}_footer" do
+      - layout = metadata.filter[:layout]
+      - if layout.is_a?(String)
+        %input{ type: 'hidden', name: 'layout', value: layout, form: post_form_id }
+        = render 'bootstrap/btn', content: t('.add', layout: site.layouts[layout].humanized_name), form: post_form_id, type: 'submit', class: 'm-0 mr-1'
+      - else
+        - layouts   = layout&.map { |x| site.layouts[x] }
+        - layouts ||= site.layouts.values
+        .input-group.w-auto.flex-grow-1.my-0
+          %select.form-control{ form: post_form_id, name: 'layout' }
+            - layouts.each do |layout|
+              %option{ value: layout.name }= layout.humanized_name
+          .input-group-append
+            = render 'bootstrap/btn', content: t('.add', layout: ''), form: post_form_id, type: 'submit', class: 'mb-0 mr-0'
+      = render 'bootstrap/btn', content: t('.accept'), action: 'array#accept modal#hide', class: 'm-0 mr-1'
+      = render 'bootstrap/btn', content: t('.cancel'), action: 'array#cancel modal#hide', class: 'm-0'
+
+-#
+  Este segundo modal es el que carga los formularios de
+  creación/modificación de artículos relacionados. Se envía a post_form
+  para que sea externo al formulario actual.
+- content_for :post_form do
+  %form{ id: post_form_id, 'hx-get': site_posts_form_path(site), 'hx-target': "##{post_form_loaded_id}" }
+    %input{ type: 'hidden', name: 'show', value: post_modal_id }
+    %input{ type: 'hidden', name: 'hide', value: modal_id }
+    %input{ type: 'hidden', name: 'target', value: value_list_id }
+    %input{ type: 'hidden', name: 'swap', value: 'beforeend' }
+    %input{ type: 'hidden', name: 'base', value: id }
+    %input{ type: 'hidden', name: 'name', value: name }
+    %input{ type: 'hidden', name: 'form', value: form_id }
+    %input{ type: 'hidden', name: 'attribute', value: metadata.type }
+    - if metadata.inverse?
+      %input{ type: 'hidden', name: 'inverse', value: metadata.inverse }
+  %div{ id: post_modal_id, data: { controller: 'modal' } }
+    = render 'bootstrap/modal', id: post_id, modal_content_attributes: { class: 'h-100' } do
+      - content_for :"#{post_id}_body" do
+        %div{ id: post_form_loaded_id }
+      - content_for :"#{post_id}_footer" do
+        = render 'bootstrap/btn', form: form_id, content: t('.save'), type: 'submit'
+        -# @todo: Volver al otro modal
+        = render 'bootstrap/btn', content: t('.cancel'), action: 'modal#hide'
diff --git a/app/views/posts/attributes/_new_has_many.haml b/app/views/posts/attributes/_new_has_many.haml
index 54eb8d40..724f8247 100644
--- a/app/views/posts/attributes/_new_has_many.haml
+++ b/app/views/posts/attributes/_new_has_many.haml
@@ -87,6 +87,7 @@
     %input{ type: 'hidden', name: 'base', value: id }
     %input{ type: 'hidden', name: 'name', value: name }
     %input{ type: 'hidden', name: 'form', value: form_id }
+    %input{ type: 'hidden', name: 'attribute', value: metadata.type }
     - if metadata.inverse?
       %input{ type: 'hidden', name: 'inverse', value: metadata.inverse }
   %div{ id: post_modal_id, data: { controller: 'modal' } }
diff --git a/app/views/posts/new_belongs_to_value.haml b/app/views/posts/new_belongs_to_value.haml
new file mode 100644
index 00000000..ab324763
--- /dev/null
+++ b/app/views/posts/new_belongs_to_value.haml
@@ -0,0 +1,2 @@
+.mb-2{ data: { target: 'array.item', 'searchable-value': @value.remove_diacritics.downcase, value: @uuid } }
+  = render 'bootstrap/custom_checkbox', name: @name, id: "value-#{Nanoid.generate}", value: @uuid, checked: true, content: @value, type: 'radio'