Not sure if this is the best way but, solved my issue by having a script on a table pre write SO_Details and then another script column post val on the BO qty.  Both scripts below.

rVal = 0
nOrdered = 0
sKit = ""
sVend = ""


rVal = oBusObj.GetValue("SkipPrintCompLine$", sKit)
rVal = oBusObj.GetValue("QuantityOrdered", nOrdered)
rVal = oBusObj.GetValue("VendorNo$", sVend)

if sKit = "Y" and sVend = "" then

rVal = oBusObj.SetValue("UDF_QTY_PULLED", nOrdered)


end if

rVal = 0
nOrdered = 0
nBO = 0
sKit = ""
sVend = ""


rVal = oBusObj.GetValue("SkipPrintCompLine$", sKit)
rVal = oBusObj.GetValue("QuantityBackordered",nBO)

if sKit = "Y" and nBO <> 0 then

rVal = oBusObj.SetValue("UDF_QTY_PULLED", 0)

end if

In a line script, you can use oHeaderObj.GetValue to access header fields like OrderType.  That would allow you to configure conditional logic, applied to Backorders (...OrderType = B).

We are not using the BO qty field like it should be, so a SO could have a BO qty and the order type still be =S.

Then build your condition on whether the QtyBO is non-zero?

The column script fires before the pre-write, so I'd think it would be possible to build everything into the pre-write... but if you have something working, there is no need to change it.

I thought I had something, scripts work when manually entering the kits and they explode, had orders import in this morning and the scripts didn't fire.  I can't seem to get any scripts to fire on kit component lines when imported, I've tried table-prewrite, table post-write, column post val on qty ordered.  Started thinking the actual kit item does not have any OH inventory so when the line imports it put a qty in the BO qty field on the kit item, then when it explodes all the components get the BO qty populated just like the actual kit item code.  The function to BO if an item is not in stock is a SAGE function, could by script to ignore that function if the item is a kit item code?  Maybe that would work on the imported lines?

Some Sage programming bypasses certain script events, and it looks like you found one. 

When that happens to me, I consider a different approach (like a header PreTotals script that loops through lines, with all the script conditions / logic there... being careful to avoid an endless recursion issue).

I got a pretotal to work but it seems like another pretotal script I have on the SOH is not getting triggered due to either this pretotal or it does not like the kit component lines.

Didn't finish my thought, we are exploding the kit when the line is entered, is it possible to not automatically explode the kit on the lines and only explode it on the "pick sheet"?

Exploding the kit components in the SO determines how inventory is depleted.  Explode: component inventory is depleted during shipping.  Don't explode: the parent item's inventory is depleted.  You can do a sub-report on a form to print a recipe for the parent item (without exploding the kit) but that won't change how inventory is consumed during shipping.

For multiple scripts on the same event, make sure each one uses a distinct Priority value, otherwise they merge when compiled... which can be bad.

Yes, aware of the priority issues due to previous experiences.  Could you glaze over both of these scripts (both on table-pre-total) to see if anything stands out, I put the "SOH_KIT" script on priority 500 to run first then the "allocate" script on 600.  The "SOH_KIT" script runs for the kit lines, however I can't get the allocate script to run initially, if I make some edits to the lines and go back it will fire off. I am not positive on the SOH_KIT script, I feel like it is missing something because it runs every time I tab over the lines tab to totals in the debug environment.  In DFDM my udf's equal the udf for line totals so the second script is true (component lines trigger udf's) just not firing.

If oSession.CompanyCode = "TST" and oBusObj.EditState = 2then
r=oScript.DebugPrint("COMPANY:" & oSession.CompanyCode)
r=oScript.DebugPrint("EDIT STATE:" & oBusObj.EditState)
rVal = 0
nOrdered = 0
sKit = ""
nBO = 0

	Set oLines = oSession.AsObject(oBusObj.Lines)
	r=oScript.DebugPrint("After oSession.GetObj")
		
	rVal = oLines.MoveFirst()
	Do Until cBool(oLines.EOF) 'Keep looping until record pointer is on last line

	rVal = oLines.GetValue("SkipPrintCompLine$", sKit)
	rVal = oLines.GetValue("QuantityOrdered", nOrdered)
	rVal = oLines.GetValue("QuantityBackordered", nBO)
	r=oScript.DebugPrint("Component: " & sKit)
	r=oScript.DebugPrint("QuantityOrdered:" & nOrdered)
	r=oScript.DebugPrint("QuantityBackordered:" & nBO)
			
		if sKit = "Y" and nBO = 0 then

		rVal = oLines.SetValue("UDF_QTY_PULLED", nOrdered)
		rVal = oLines.Write()
		r=oScript.DebugPrint("rVal on oLines Write: " & CStr(rVal))

		
		end if
	rVal = oLines.MoveNext()
	Loop
end if

rVal = 0
nRec = 0
nPull = 0
nUnits = 0
nTotal = 0
sType = ""
dToday = ""

rVal = oBusObj.GetValue("OrderType$", sType)

if sType = "S" Or sType = "B" then

rVal = oBusObj.GetValue("UDF_TOTAL_QTY_REC", nRec)
rVal = oBusObj.GetValue("UDF_TOTAL_QTY_PULLED", nPull)
rVal = oBusObj.GetValue("UDF_UNIT_COUNT", nUnits)

nTotal = nRec+nPull

	if nTotal = nUnits then

	rVal = oBusObj.SetValue("UDF_ALLOCATED$", "Y")
	rVal = oSession.FormatDate(oSession.SystemDate, dToday, "%M/%D/%Y")
	
	dToday = oSession.GetFormattedDate(CStr(dToday))	

	rVal = oBusObj.SetValue("UDF_DATE_ALLOCATED$", dToday)

	end if

end if