Hi Dhiraj,
Going through your Step2, it seems that you are looking for a journal entry to be done, once the SD payment is released so that the initial GL A/c, (say X001) is settled and the balance is transferred to a new GL A/c (Say X002).
I guess you are performing the SD release only at the time of Final Invoicing and not on an ad-hoc basis through FPSEC2.
If so, then you can go to the following SPRO config-
IMG--->SAP Utilities--->Invoicing--->Invoice Processing-->Item Selection in Invoicing--->Item selection in Account maintenance/Define Sub Items
Select the Clearing type, either R42/R43 (depending on your Business Process) and click on "Item Selection for Bill Printout (Sub Items)".
Select the SD payment main\sub combination (as per standard SAP-0020/0010) and check the box "Transfer to Credit memo/Receivable for Consumption Billing"
This checkbox controls whether a document which has already been posted should be transferred to a consumption billing credit memo/receivable in invoicing.
The newly generated document inherits the due date of the invoicing document.
Hope it helps..
Thanks,
Amlan