Didn't know the answer to this off the top of my head, but here's what GPT has to say about it:

Yes, when a user deletes all the text in a form field, Word removes the associated bookmark. To prevent this while allowing users to edit the fields, you can use VBA to restore the bookmark if it is deleted. Here are a few approaches:

**Solution 1: Use VBA to Restore the Bookmark**
You can create a macro that runs when the document is opened or before printing to check for missing bookmarks and restore them if needed.

**Steps:**
1. Open the VBA Editor (`Alt + F11`).
2. Insert a new module.
3. Add the following code:

Code

Sub RestoreBookmarks()
    Dim bm As Bookmark
    Dim rng As Range
    Dim bmName As String

    ' List of bookmarks to check
    Dim bmList As Variant
    bmList = Array("Bookmark1", "Bookmark2", "Bookmark3") ' Update with your bookmark names

    For Each bmName In bmList
        If ActiveDocument.Bookmarks.Exists(bmName) = False Then
            ' Restore the bookmark at its original position
            Set rng = ActiveDocument.Range
            rng.Collapse wdCollapseEnd
            rng.Text = "[Placeholder]" ' Insert placeholder text
            ActiveDocument.Bookmarks.Add bmName, rng
        End If
    Next bmName
End Sub
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4. Run this macro manually or set it to trigger on `Document_Open` or `Document_BeforeSave`.

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**Solution 2: Use a Macro-Enabled Form Field**
If you're using form fields (`Legacy Form Fields`), you can modify them to prevent the deletion of bookmarks.

**Steps:**
1. Double-click on the form field to open Form Field Options.
2. Check Calculate on exit.
3. Add the following VBA code in the VBA Editor (`Alt + F11`):

Code

Private Sub Document_ContentControlOnExit(ByVal ContentControl As ContentControl, Cancel As Boolean)
    Dim bmName As String
    bmName = ContentControl.Title ' Ensure the Content Control has a Title matching the bookmark name
    
    ' Restore bookmark if deleted
    If ActiveDocument.Bookmarks.Exists(bmName) = False Then
        ActiveDocument.Bookmarks.Add bmName, ContentControl.Range
    End If
End Sub
Copy

This ensures the bookmark is automatically recreated when the user exits the field.

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**Solution 3: Use a Content Control Instead of a Form Field**
If possible, use Content Controls instead of Form Fields, as they retain bookmarks even when cleared.

**Steps:**
1. Unlock the document and replace the form fields with Rich Text Content Controls.
2. Set each control's Tag or Title to match the bookmark name.
3. Protect the document again.

Since Content Controls don't remove bookmarks when cleared, this method is the simplest if it suits your workflow.

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**Summary**
- Use VBA to check and restore missing bookmarks (`RestoreBookmarks` macro).
- Enable "Calculate on Exit" in form fields to force re-evaluation.
- Use Content Controls instead of form fields to avoid deletion issues.