Hi Bala
If you need both order and deliveries linked in 1 cube you should go for 2lis_12_vcitm and 2lis_11_VASCL.
First create two DSO D1 and D2 for each 2lis_12_vcitm and 2lis_11_vascl with key Delivery,Delivery Item and Order ,Order Item repectively.
Then create a comon dso D3 and load from D1 and D2, D3 will have keys Sales order and item.
Note - when you map D1(delivery DSO 1) with D3 - map order,item from D3 with ref document and ref item from D1.
You can get all the fields you want . if you need any processing/logic and want to use order item datasource for the same, then you should load this data in a separate DSO and use it in start/end routine in aformentioned flow wherever you may desire.
This is a robust and tested design we are using.
Regards