Rails 3 - Nested Forms, using Builder -- Check_box issue

Hello, I have the following:

My Controller:

      def new
    .
    .
        @teammembers.each do |teammember|
            request = @request_thread.requests.build(:recipient_id =>
teammember.user_id, :full_name => 'Billy Bob T')
        end

My View:
.
.
  <%= f.fields_for :requests do |builder| %>

    <div class="field">
      <%= builder.label :full_name %>
      <%= builder.check_box :recipient_id, :checked => false %>
    </div>
  <% end %>
.
.
The nested form for requests only holds the user_id, not the
user.name... Problem is in the nested form, I need to show the
user.name next to the check_box. So I tried adding a virtual attribute
in the model (attr_accessor :full_name), so I could use full_name but
I can't see to access that in the nested form (inside builder).

Also, the checkbox doesn't have the recipient_id as the value being
set? I want to use the checkbox to tell Rails whether or not to create
the record or not on submit using something like this in the model
":reject_if => lambda { |a| a[:recipient_id].blank? }"

Anyone with fields_for experience?

Any tips or suggestions from the pros?

Thanks

Follow-up, in the nested form if I have:

    <div class="field">
      <%= item.label :recipient_id %>
      <%= item.text_field :recipient_id %>
      <%= item.check_box :recipient_id %>
    </div>

I get an output of

<div class="field">
<label
for="request_thread_requests_attributes_1_recipient_id">Recipient</

<input id="request_thread_requests_attributes_1_recipient_id"
name="request_thread[requests_attributes][1][recipient_id]" size="30"
type="text" value="61">
<input name="request_thread[requests_attributes][1][recipient_id]"
type="hidden" value="0"><input checked="checked"
id="request_thread_requests_attributes_1_recipient_id"
name="request_thread[requests_attributes][1][recipient_id]"
type="checkbox" value="1">
</div>

So the ID I want is working for text_field but not check_box

Shouldn't this work: "<%= item.check_box :recipient_id, :value
=> :recipient_id %>"

That outputs:
<input checked="checked"
id="request_thread_requests_attributes_1_recipient_id"
name="request_thread[requests_attributes][1][recipient_id]"
type="checkbox" value="1">

the value is wrong. All the checkboxes show value 1. Yet, this "<%=
item.text_field :recipient_id %>" gets the right value?