My objective of this project is to have my co-workers,
who are not familiar with Access, to input data in Excel.
Meanwhile I will either establish a link or a macro to
transfer data to Access which, at the end will be picked
up by Crystal Report to produce a report. I have made two
unsuccessful attempts.

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Attempt # 1)

I made a link between Access and Excel so that when
information changed in Excel will change in Access and
vice versa. Steps that I used was

-From Access, FILE, GET EXTERNAL DATA
-Select LINK TABLES.
-Choose Excel directory
-Choose file type EXCEL
-Press LINK
-Press NEXT
-Name the table name as the table name I had in Access
-Press NEXT
-Press FINISH

However, when I went to Access trying to change my data
definition from FIELD PROPERTIES, I realized that I was
not able to set any of my fields as Indexed field. As a
result, I was not able to work out links in Crystal
Report.

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Attempt # 2)  which would be a much better solution if
work out.

I also tried to achieve such task by using Macro in Excel:

Sub ADOFromExcelToAccess()
' exports data from the active worksheet to a table in an
Access database
' this procedure must be edited before use
Dim cn As ADODB.Connection, rs As ADODB.Recordset, r As
Long
   ' connect to the Access database
   Set cn = New ADODB.Connection
   cn.Open "Provider=Microsoft.Jet.OLEDB.4.0; " & _
       "Data Source=C:\FolderName\DataBaseName.mdb;"
   ' open a recordset
   Set rs = New ADODB.Recordset
   rs.Open "TableName", cn, adOpenKeyset,
adLockOptimistic, adCmdTable
   ' all records in a table
   r = 3 ' the start row in the worksheet
   Do While Len(Range("A" & r).Formula) > 0
   ' repeat until first empty cell in column A
       With rs
           .AddNew ' create a new record
           ' add values to each field in the record
           .Fields("FieldName1") = Range("A" & r).Value
           .Fields("FieldName2") = Range("B" & r).Value
           .Fields("FieldNameN") = Range("C" & r).Value
           ' add more fields if necessary...
           .Update ' stores the new record
       End With
       r = r + 1 ' next row
   Loop
   rs.Close
   Set rs = Nothing
   cn.Close
   Set cn = Nothing
End Sub

Nevertheless with such Macro I could only transfer the
whole Excel database into Access in addition to of what I
already (i.e.: duplicate) have instead of updating/
replacing it.

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Can anyone please give me a solution on either to
identify the INDEXED FIELD in Access while linked to
Excel or add a command in the Macro in order to avoid
duplication when the Macro is run?