Thank you, everyone.  Got the bones of this in working order.  I still have work to do, but here is the code in case anyone is searching the forums in the future.

'to be triggered on column post validate of UDF_GenerateBO in Invoice Data Entry
'Creates a copy of the order being invoiced

'retval = CopyFromOrder(order$, type$, clearJob, copyMemos)

retval = 0
sSO = ""
sNewSO = ""

retval = oBusObj.GetValue("SalesOrderNo$", sSO)

oSO = oSession.GetObject("SO_SalesOrder_Bus")

sNewSO = "B" & right(sSO,6)

retVal = oSession.AsObject(oSession.UI).MessageBox("SO No: " & sSO & vbcrlf & "New SO: " & sNewSO)

if oSO <> 0 then

set oSO = oSession.AsObject(oSO)

'retval = oSO.CopyFromOrderHistory(sSO, "S", 0, 0)

'retval = oSO.GetNextSalesOrderNo(sNewSO)

retval = oSO.SetKey(sNewSO)
if retval = 0 then
retVal = oSession.AsObject(oSession.UI).MessageBox("*" & oSO.LastErrorMsg)
end if

retval = oSO.CopyFromOrder(sSO, "S", 0, 0)
if retval = 0 then
retVal = oSession.AsObject(oSession.UI).MessageBox("*" & oSO.LastErrorMsg)
end if


retVal = oSO.Write()
if retval = 0 then
retVal = oSession.AsObject(oSession.UI).MessageBox("*" & oSO.LastErrorMsg)
end if

end if

I'm somewhat curious why you wouldn't just let Sage generate the BO automatically as you post the invoice.

I'm somewhat curious why you wouldn't just let Sage generate the BO automatically as you post the invoice.

Fair question.  It takes some time before each invoice is finalized with tracking info, etc. and we often need to be able to begin shipping the remainder of the order before the first invoice is posted.  Sage will not allow you to ship against an order if there is a pending invoice for the same order.

You can import tracking after the invoice is posted, if that is the issue.  We do it in a few places.