<fieldset>
  <%= form.label :related_policy_ids, "Parent policy" %>
  <p class="help-block">Choose which policy this page will appear on. (You
  should rarely choose more than one policy).</p>

  <%= form.select :related_policy_ids,
                  options_from_related_policy_options_for_select(related_policy_options, form.object),
                  { include_blank: true },
                  multiple: true,
                  class: "chzn-select",
                  data: { placeholder: "Choose related policies..."} %>
</fieldset>

Rename related policies field for supporting pages
Rename related policies field for supporting pages

Be more explicit that it's a stronger relationship than related
policies normally are. Point out that multiple policies shouldn't be
common.
