Thanks TW for the suggestion. I did that yesterday and Split is not happening. I am able to run the scenario now till return Invoice. Return Invoice is not released to accounting as R100 is not assigned to COPA values.
Now I have few more questions
a) While I have not assigned R100 to COPA value field, How system allowed to release the original invoice before and now throwing error while doing the return invoice
b) As per my expectation,the Free goods are flowing with net value 0 from sales order to return invoice. What I wonder is about the values of COGS and Inventory account. The G/L posting for both are showing in all the line items(TAN/TANN). In brief, the free goods independent line item also show the COGS/Inventory ac values for all the line items(Including Main item).
Reg