diff --git a/app/controllers/posts_controller.rb b/app/controllers/posts_controller.rb
index 6d199cd7..282a784a 100644
--- a/app/controllers/posts_controller.rb
+++ b/app/controllers/posts_controller.rb
@@ -40,10 +40,18 @@ class PostsController < ApplicationController
     render layout: false
   end
 
-  # El formulario de un Post, si pasamos el uuid, estamos editando, sino
+  def new_has_one
+    @uuid = params.require(:value).strip
+
+    @indexed_post = site.indexed_posts.find_by!(post_id: @uuid)
+
+    render layout: false
+  end
+
+  # El formulario de un Post, si pasamos el UUID, estamos editando, sino
   # estamos creando.
   def form
-    uuid = params.permit(:uuid).try(:[], :uuid)
+    uuid = params.permit(:uuid).try(:[], :uuid).presence
     locale
 
     @post =
@@ -111,7 +119,7 @@ class PostsController < ApplicationController
                               params: params)
     @post = service.create
 
-    if @post.persisted?
+    if post.persisted?
       site.touch
       forget_content
     end
@@ -119,11 +127,11 @@ class PostsController < ApplicationController
     # @todo Enviar la creación a otro endpoint para evitar tantas
     # condiciones.
     if htmx?
-      if @post.persisted?
+      if post.persisted?
         swap_modals
 
-        @value = @post.title.value
-        @uuid = @post.uuid.value
+        @value = post.title.value
+        @uuid = post.uuid.value
         @name = params.require(:name)
 
         render render_path_from_attribute, layout: false
@@ -133,8 +141,8 @@ class PostsController < ApplicationController
 
         render 'posts/form', layout: false, post: post, site: site, **params.permit(:form, :base, :dir, :locale)
       end
-    elsif @post.persisted?
-      redirect_to site_post_path(@site, @post)
+    elsif post.persisted?
+      redirect_to site_post_path(site, post)
     else
       render 'posts/new'
     end
@@ -235,7 +243,7 @@ class PostsController < ApplicationController
   # @param triggers [Hash] Otros disparadores
   def swap_modals(triggers = {})
     params.permit(:show, :hide).each_pair do |key, value|
-      triggers["modal:#{key}"] = { id: value }
+      triggers["modal:#{key}"] = { id: value } if value.present?
     end
 
     headers['HX-Trigger'] = triggers.to_json if triggers.present?
@@ -247,6 +255,7 @@ class PostsController < ApplicationController
     when 'new_has_many' then 'posts/new_has_many_value'
     when 'new_belongs_to' then 'posts/new_belongs_to_value'
     when 'new_has_and_belongs_to_many' then 'posts/new_has_many_value'
+    when 'new_has_one' then 'posts/new_has_one_value'
     else 'nothing'
     end
   end
diff --git a/app/javascript/controllers/modal_controller.js b/app/javascript/controllers/modal_controller.js
index 20154f79..0f8deeca 100644
--- a/app/javascript/controllers/modal_controller.js
+++ b/app/javascript/controllers/modal_controller.js
@@ -18,9 +18,23 @@ export default class extends Controller {
     window.removeEventListener("modal:hide", this.hideEvent);
   }
 
+  /*
+   * Abrir otro modal, enviando el ID a toda la ventana.
+   */
+  showAnother(event = undefined) {
+    event?.preventDefault();
+
+    if (!event.target?.dataset?.modalShowValue) return;
+
+    window.dispatchEvent(new CustomEvent("modal:show", { detail: { id: event.target.dataset.modalShowValue } }));
+  }
+
   /*
    * Podemos enviar la orden de apertura como un click o como un
    * CustomEvent incluyendo el id del modal como detail.
+   *
+   * El elemento clicleable puede tener un valor que se refiera a otro
+   * modal también.
    */
   show(event = undefined) {
     event?.preventDefault();
diff --git a/app/models/metadata_new_has_one.rb b/app/models/metadata_new_has_one.rb
new file mode 100644
index 00000000..642273e3
--- /dev/null
+++ b/app/models/metadata_new_has_one.rb
@@ -0,0 +1,6 @@
+# frozen_string_literal: true
+
+# Nueva interfaz para relaciones 1:1
+class MetadataNewHasOne < MetadataHasOne
+  include Metadata::UnusedValuesConcern
+end
diff --git a/app/views/posts/_htmx_form.haml b/app/views/posts/_htmx_form.haml
index 707b9c51..f4f4a845 100644
--- a/app/views/posts/_htmx_form.haml
+++ b/app/views/posts/_htmx_form.haml
@@ -61,8 +61,8 @@
               = errors.first
 
   -# Parámetros para HTMX
-  %input{ type: 'hidden', name: 'hide', value: params.require((post.errors.empty? ? :show : :hide)) }
-  %input{ type: 'hidden', name: 'show', value: params.require((post.errors.empty? ? :hide : :show)) }
+  %input{ type: 'hidden', name: 'hide', value: params.permit((post.errors.empty? ? :show : :hide)).try(:values).try(:first) }
+  %input{ type: 'hidden', name: 'show', value: params.permit((post.errors.empty? ? :hide : :show)).try(:values).try(:first) }
   %input{ type: 'hidden', name: 'name', value: params.require(:name) }
   %input{ type: 'hidden', name: 'base', value: params.require(:base) }
   %input{ type: 'hidden', name: 'form', value: options[:id] }
diff --git a/app/views/posts/_new_has_one.haml b/app/views/posts/_new_has_one.haml
new file mode 100644
index 00000000..54a370cd
--- /dev/null
+++ b/app/views/posts/_new_has_one.haml
@@ -0,0 +1,2 @@
+= render 'posts/new_related_post', post: post
+%input{ type: 'hidden', name: name, value: value }
diff --git a/app/views/posts/attribute_ro/_new_has_one.haml b/app/views/posts/attribute_ro/_new_has_one.haml
new file mode 100644
index 00000000..425e659e
--- /dev/null
+++ b/app/views/posts/attribute_ro/_new_has_one.haml
@@ -0,0 +1,6 @@
+%tr{ id: attribute }
+  %th= post_label_t(attribute, post: post)
+  %td{ dir: dir, lang: locale }
+    - p = metadata.has_one
+    - if p
+      = link_to p.title.value, site_post_path(site, p.id)
diff --git a/app/views/posts/attributes/_new_has_one.haml b/app/views/posts/attributes/_new_has_one.haml
new file mode 100644
index 00000000..5a614990
--- /dev/null
+++ b/app/views/posts/attributes/_new_has_one.haml
@@ -0,0 +1,53 @@
+-#
+  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 = random_id
+  name = "#{base}[#{attribute}]"
+  target_id = random_id
+  form_id = random_id
+  modal_id = random_id
+  post_id = random_id
+  post_form_id = random_id
+  post_modal_id = random_id
+  post_form_loaded_id = random_id
+  value_list_id = random_id
+  layout = metadata.filter[:layout]
+
+%div{ data: { controller: 'modal'  }}
+  .form-group
+    = hidden_field_tag name, ''
+    .d-flex.align-items-center.justify-content-between
+      = label_tag id, post_label_t(attribute, post: post), class: 'h3'
+      = render 'bootstrap/btn', content: t('.edit'), action: 'modal#showAnother', data: { 'modal-show-value': modal_id }
+
+  -# Aquí se reemplaza por la tarjeta y el UUID luego de guardar
+  .row.row-cols-1.no-gutters.placeholder-glow{ id: target_id }
+    -# @todo issue-7537
+    - if !metadata.empty? && (indexed_post = site.indexed_posts.find_by(post_id: metadata.value))
+      = render 'posts/new_has_one', post: indexed_post, name: name, value: metadata.value
+
+-#
+  El modal se genera por fuera del formulario, para poder enviar los
+  datos y recibir su UUID en respuesta.
+- content_for :post_form do
+  %div{ id: modal_id, data: { controller: 'modal'  }}
+    - if layout.is_a?(String)
+      = render 'bootstrap/modal', id: id, modal_content_attributes: { class: 'h-100' } do
+        - content_for :"#{id}_body" do
+          -# @todo ocultar el modal después de guardar
+          .placeholder-glow{ 'hx-get': site_posts_form_path(site, layout: layout, base: id, name: name, form: form_id, swap: 'innerHTML', target: target_id, attribute: 'new_has_one', hide: modal_id, uuid: metadata.value), 'hx-trigger': 'load' }
+            %span.placeholder.w-100.h-100
+
+        - content_for :"#{id}_footer" do
+          = render 'bootstrap/btn', form: form_id, content: t('.save'), type: 'submit', class: 'm-0 mt-1 mr-1'
+          = render 'bootstrap/btn', content: t('.cancel'), action: 'modal#hide', class: 'm-0 mt-1 mr-1'
+
+    - else
+      Nada
diff --git a/app/views/posts/new_has_one.haml b/app/views/posts/new_has_one.haml
new file mode 100644
index 00000000..e32f191b
--- /dev/null
+++ b/app/views/posts/new_has_one.haml
@@ -0,0 +1 @@
+= render 'posts/new_has_one', post: @indexed_post, name: params.require(:name), value: @uuid
diff --git a/app/views/posts/new_has_one_value.haml b/app/views/posts/new_has_one_value.haml
new file mode 100644
index 00000000..9f2b660a
--- /dev/null
+++ b/app/views/posts/new_has_one_value.haml
@@ -0,0 +1 @@
+= render 'posts/new_has_one', post: @post.to_index, name: params.require(:name), value: @uuid
diff --git a/config/routes.rb b/config/routes.rb
index 45410782..711e3f24 100644
--- a/config/routes.rb
+++ b/config/routes.rb
@@ -103,6 +103,7 @@ Rails.application.routes.draw do
         get :'posts/new_array', to: 'posts#new_array'
         get :'posts/new_array_value', to: 'posts#new_array_value'
         get :'posts/new_related_post', to: 'posts#new_related_post'
+        get :'posts/new_has_one', to: 'posts#new_has_one'
         get :'posts/form', to: 'posts#form'
 
         resources :posts do