Been trying for a long time to make this work. Here's my starting xml:

<root>
  <a>top 1</a>
  <b>b 110</b>
  <b>b 111</b>
  <b>b 112</b>
  <c>c 11</c>
  <b>b 120</b>
  <b>b 121</b>
  <c>c 12</c>
  <b>b 130</b>
  <b>b 131</b>
  <b>b 132</b>
  <b>b 133</b>
  <c>c 13</c>
  <b>b 140</b>
  <c>c 14</c>
  <a>top 2</a>
  <b>b 210</b>
  <b>b 211</b>
  <b>b 212</b>
  <c>c 21</c>
  <b>b 220</b>
  <b>b 221</b>
  <c>c 22</c>
</root>

And here is the xml I want to end up:

<root>
  <a>top 1
    <c>c 11
      <b>b 110</b>
      <b>b 111</b>
      <b>b 112</b>
    </c>
    <c>c 12
      <b>b 120</b>
      <b>b 121</b>
    </c>
    <c>c 13
      <b>b 130</b>
      <b>b 131</b>
      <b>b 132</b>
      <b>b 133</b>
    </c>
    <c>c 14
      <b>b 140</b>
    </c>
  </a>
  <a>top  2
    <c>c 21
      <b>b 210</b>
     <b>b 211</b>
     <b>b 212</b>
    </c>
    <c>c 22
      <b>b 220</b>
      <b>b 221</b>
    </c>
  </a>
</root>

I've tried a lot of things. It's hard to move the c element up to be a
parent of b.

Thanks if anyone can figure it out :)

Craig