Access VBA Error trying to create column for linked table

In trying to create an Access column in a linked table I get the error "Operation is not supported in linked tables"
Is there a way to do this where the tables are linked

Sub oCheck_Add_Columns()

    Dim dbs As DAO.Database
    Dim tdf As DAO.TableDef
    Dim fld As DAO.Field
    Dim blnFieldExists As Boolean
    Set dbs = CurrentDb()
    Set tdf = dbs.TableDefs("Ammunition")
    For Each fld In tdf.Fields
        If fld.Name = "CreatedDTG" Then
            blnFieldExists = True
            Exit For
        End If
    Next
   
    If Not blnFieldExists Then
        Set fld = tdf.CreateField("CreatedDTG", dbDate)
        fld.DefaultValue = "=Now()"
        tdf.Fields.Append fld
    End If
   
End Sub