title: Prevent Excel from deleting reference in formula when row is deleted
body: <p>I have an Excel workbook with worksheets <code>Sheet1</code> and <code>Sheet2</code>, where <code>Sheet2</code> has formulas that refer to values in <code>Sheet1</code> as follows:</p>
  
  <pre><code>+-----------+------------+
  |  address  |   value    |
  +-----------+------------+
  | Sheet1!A1 | 1          |
  | Sheet1!B1 | 3          |
  | Sheet1!C1 | 5          |
  | Sheet2!A1 | =Sheet1!A1 |
  | Sheet2!B1 | =Sheet1!B1 |
  | Sheet2!C1 | =Sheet1!C1 |
  +-----------+------------+
  </code></pre>
  
  <p>If I delete row 1 from <code>Sheet1</code>, using the following C# interop:</p>
  
  <pre><code>thisRange["a1"].EntireRow.Delete()
  </code></pre>
  
  <p>then all the formulas get set to errors, e.g. <code>=Sheet1!#REF!</code>.</p>
  
  <p>Is there a way to preserve the existing references in the formulas once the row is deleted?  I suppose I could copy all the formulas into an array and then recopy them into the sheet, but I'd ideally like to have them not disappear in the first place.  </p>