Simple query question but it eludes me...

 Hello all,
I am trying to write a query to to find out how many closed, multiple deliveries sales orders by org.

Currently it looks like this:
select count (SOURCE_HEADER_NUMBER)
from wsh_delivery_details WDD, OE_ORDER_HEADERS_ALL OEH
WHERE WDD.RELEASED_STATUS = 'C'
AND WDD.ORG_ID = '122'
AND WDD.SOURCE_HEADER_ID = OEH.HEADER_ID

I believe this is giving me all the shipments for each given SO.  Right?

So how do I segregate just the multiple deliveries?

Thanks for your help.