Returns a TextRange object that represents a mail merge field.
expression.InsertMailMergeField(varIndex)
expression Required. An expression that returns one of the objects in the Applies To list.
varIndex Required Variant. The name of the field.
This example inserts a LastName field at the cursor position. This example assumes that the active publication is a mail merge publication and that the insertion point is somewhere inside a text box.
Sub InsertMergeField()
Selection.TextRange.InsertMailMergeField varIndex:="LastName"
End Sub