<h1>Add a new Item</h1>
<%= form_for [@list, @item] do |f| %>
  Item Name: <%= f.text_field :name  %>
  <%= f.submit  %>
<% end %>

<h1>Add a new Item</h1>
<%= form_for [@list, @item] do |f| %>
  Item Name: <%= f.text_field :name  %>
  <p>Item Name: <%= f.text_field :name  %></p>
  <%= fields_for @store do |store| %>
    <p>Store Name: <%= store.text_field :name  %></p>
  <% end %>
  <%= f.submit  %>
<% end %>

Include Store on new Item form
Include Store on new Item form
