Richard:

Rather than using a form and inserting rows into a auxiliary table why not
use two multi-select list boxes on a single unbound form, lstAssistFMJobNo
and lstAssistSiteRef say.  You can then build a filter for the report in the
Click event procedure of a button on the form.

First set up the list boxes to list the AssistFMJobNo and AssistSiteRef
values from the tblNapsWork table in order and set the MultiSelect property
of each list box to Simple or Extended as desired; the former allows multiple
selection/deselection by simple clicking on each item one by one, the latter
allows multiple selection by cttl+click or shift+click in the standard
Windows way.

The button would loop through the ItemsSelected collection of each list box
and built a string expression which can then be used as the WhereCondition
setting of the OpenReport method:

   Dim varItem As Variant
   Dim strAssistFMJobNoList As String
   Dim strAssistSiteRefList As String
   Dim strCriteria As String
   Dim ctrl As Control
   
   Set ctrl = Me.lstAssistFMJobNo
   
   ' loop through lstAssistFMJobNo list box's ItemsSelected collection
   ' and build comma separated list of selected items
   If ctrl.ItemsSelected.Count > 0 Then
       For Each varItem In ctrl.ItemsSelected
           strAssistFMJobNoList = strAssistFMJobNoList & "," &
ctrl.ItemData(varItem)
       Next varItem
       
       ' remove leading comma
       strAssistFMJobNoList = Mid(strAssistFMJobNoList, 2)
       
       strCriteria = "AssistFMJobNo In(" & strAssistFMJobNoList & ")"
   End If

   ' if any AssistFMJobNo items selected insert an
   ' OR operator in criteria string expression
   If len(strCriteria) > 0 Then
       strCriteria = strcriteria & " Or "
   End If

   Set ctrl = Me.lstAssistSiteRef

   ' loop through lstAssistSiteRef list box's ItemsSelected collection
   ' and build comma separated list of selected items
   If ctrl.ItemsSelected.Count > 0 Then
       For Each varItem In ctrl.ItemsSelected
           strAssistSiteRefList = strAssistSiteRefList & "," &
ctrl.ItemData(varItem)
       Next varItem
       
       ' remove leading comma
       strAssistSiteRefList = Mid(strAssistSiteRefList, 2)
       
       strCriteria = strCriteria  & "AssistSiteRef In(" &
strAssistSiteRefList & ")"
   End If

   ' inform user if no items selected
   If Len(strCriteria) = 0 Then
       MsgBox "No items selected.", vbExclamation, "Invalid Operation"
   Else
       ' open report
       DoCmd.OpenReport "YourReportNameGoesHere", _
           View:=acViewPreview, _
           WhereCondition:=strCriteria
   End If

The above assumes that both the AssistFMJobNo and AssistSiteRef columns in
the table are of number data types.  If they were text data types then the
code would need amending to include quotes characters around the values:

strAssistFMJobNoList = strAssistFMJobNoList & ",""" & ctrl.ItemData(varItem)
& """"

and:

strAssistSiteRef = strAssistSiteRef & ",""" & ctrl.ItemData(varItem) & """"

Using list boxes like this the user can select as few or as many items from
either or both and open the report filtered by those selections.  The report
would now be based on the tblNapsWork table, without any need to include the
auxiliary tblFindAddressByJobNo table in the underlying RecordSource.

You could of course have two buttons on the form, one to preview the report
(as above) and one to print it (with View:=acViewnormal), or you could
include a check box or option group in the form to select whether to preview
or print the report and amend the code so that it previews or prints
depending on the value of the check box or option group.

If you want a button to clear the selections in the list boxes put this in
its Click event procedure:

   Dim n As Integer
   
   For n = 0 To Me.lstAssistFMJobNo.ListCount - 1
       Me.lstAssistFMJobNo.Selected(n) = False
   Next n

   For n = 0 To Me.lstAssistSiteRef.ListCount - 1
       Me.lstAssistSiteRef.Selected(n) = False
   Next n

Ken Sheridan
Stafford, England