Hello Karan,
I understand you want to capture demand(Sales Order Qty) at your original location. If you can give some more information on your requirement of Demand Retention - What is the purpose of this? Is it required for Demand Planning in APO-DP?
I know after implementations of RBA functionality, Sales order will have Main lineitem(TAPA) and Sub items(TAN) in Sales Order.
For demand retention you should not include any Sub items from Sales order, only consider main item with Item Category = TAPA.
Also you can refer this thread which I has update from me as well. I think this will give you some insight on what needs to be done.
How can TAPA item category be avoided during ATP check with RBA?
Hope this will help.
Thank you,
Satish Waghmare