サービスの定義に使うhtmlを明記

編集画面に表示要素を追加するとします

app/config/services.yml

  #
  # 管理画面 会員管理
  #
  sonata.admin.member:
    class: AppBundle\Admin\MemberAdmin
    tags:
      - { name: sonata.admin, manager_type: orm, group: "項目", label: "会員" }
    arguments:
      - ~
      - AppBundle\Entity\Member
      - ~
    calls:
      - [ setTranslationDomain, [AppBundle]]
      - [ setTemplate, [edit, admin/member/edit.html.twig]]

setTemplate で admin/member/edit.html.twig を定義

編集画面のhtmlを用意

app/Resources/views/admin/member/edit.html.twig

{% extends 'SonataAdminBundle:CRUD:base_edit.html.twig' %}

下記のファイルを参考に、必要に応じてブロックをオーバーライドする

vendor/sonata-project/admin-bundle/Resources/views/standard_layout.html.twig
vendor/sonata-project/admin-bundle/Resources/views/CRUD/base_edit.html.twig

サンプル

{% extends 'admin/base_edit.html.twig' %}

{% block form %}
{{ parent() }}
{% if admin.id(object) is not null %}
        <div class="col-md-12">
            <div class="box box-success">
                <div class="box-body">
                    <div class="sonata-ba-collapsed-fields">

                      <div class="form-group">
                        <label class="control-label">
                          年齢
                        </label>
                        <div class=" sonata-ba-field sonata-ba-field-standard-natural  ">
                          {{ object.age }}歳 ({{ object.birthday|date("Y年m月d日生まれ") }})
                        </div>
                      </div>

                      <div class="form-group">
                        <label class="control-label">
                          購入履歴
                        </label>

                        <div class="sonata-ba-field sonata-ba-field-standard-natural">
                          <table class="table table-bordered table-striped">
                            <thead>
                              <tr class="sonata-ba-list-field-header">
                                <th>注文番号</th>
                                <th>注文日時</th>
                                <th>売上金額</th>
                              </tr>
                            </thead>
                            <tbody>
                              {% for order in object.memberOrders %}
                              <tr>
                                <td><a href="{{ path('sonata_order_show', {'id': order.id}) }}">{{ order.orderId }}</a></td>
                                <td>{{ order.createdString}}</td>
                                <td>{{ order.totalString|raw }}</td>
                              </tr>
                              {% endfor %}
                            </tbody>
                          </table>
                        </div>
                      </div>
                    </div>
                </div>
            </div>
        </div>
{% endif %}
{% endblock %}