Xquery - reduce two docs into one

I am quite new to xquery and I have a FLWOR question

I have 2 different files with the same "filename" elements. I want to reduce these files into one where the same filename elements are closed together surrounded by one meta element. Furthermore the "Value" element that belong to each filename should also be inside the meta element. For better understanding here is the first file:

<FNumber>
<meta>
<Value2>2.9</Value2>
<FileName>file4</FileName>
<FileName>file5</FileName>
</meta>
<meta>
<Value2>2.8</Value2>
<FileName>file7</FileName>
<FileName>file8</FileName>
<FileName>file9</FileName>
<FileName>file14</FileName>
<FileName>file15</FileName>
<FileName>file16</FileName>
<FileName>file17</FileName>
<FileName>file18</FileName>
<FileName>file19</FileName>
</meta>
<meta>
<Value2>16.0</Value2>
<FileName>file13</FileName>
</meta>
</FNumber>


and here the second:

<FocalLength>
<meta>
<Value1>70.0mm</Value1>
<FileName>file11</FileName>
</meta>
<meta>
<Value1>7.90mm</Value1>
<FileName>file1</FileName>
<FileName>file7</FileName>
<FileName>file8</FileName>
<FileName>file9</FileName>
<FileName>file14</FileName>
<FileName>file15</FileName>
<FileName>file16</FileName>
<FileName>file17</FileName>
<FileName>file18</FileName>
<FileName>file19</FileName>
</meta>
<meta>
<Value1>6.13mm</Value1>
<FileName>file6</FileName>
</meta>
<meta>
<Value1>6.0mm</Value1>
<FileName>file3</FileName>
</meta>
</FocalLength>


There are still some meta elements missing. Now I want to put these files together to something like this


<FF>
<meta>
<Value2>2.8</Value2>
<Value1>7.90mm</Value1>
<FileName>file7</FileName>
<FileName>file8</FileName>
<FileName>file9</FileName>
<FileName>file14</FileName>
<FileName>file15</FileName>
<FileName>file16</FileName>
<FileName>file17</FileName>
<FileName>file18</FileName>
<FileName>file19</FileName>
</meta>
</FF>

So "file1" is missing, because it belongs only to Value1 but not to value2. I hope one can understand what I am trying to achieve. Hopefully someone knows how to do it.

Thanks

Sebastian

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