fields_for.html.erb

<% form_for setup_company(@company) do |f| %>
  <%= f.label :name %><br />
  <%= f.text_field :name %><br />
 
  <% f.fields_for :addresses do |address_form| %>
    <%= f.label :street %><br />
    <%= address_form.text_field :street %><br />
    <%= f.label :city %><br />
    <%= address_form.text_field :city %><br />
    <%= f.label :post_code %><br />
    <%= address_form.text_field :post_code %><br />
    <%= f.label :region %><br />
    <%= address_form.text_field :region %><br />
  <% end %>
 
  <%= f.submit %>
<% end %>