snippet.txt

class Account < ActiveRecord::Base
  has_many :users
  belongs_to :first_user, :class_name => 'User'
  
  accepts_nested_attributes_for :first_user
  
end

class AccountsController < ApplicationController
  def new
    @account = Account.new(:first_user => User.new)
    # ...
  end
  
  # ...
end


<% semantic_form_for(@account) do |f| %>
  <% f.inputs :name => 'Account' do %>
    <%= f.input :name %>
  <% end %>

  <%= f.inputs :email, :password, :password_confirmation, :for => :first_user, :name => 'User' %>
  
  <%= f.buttons %>
<% end %>