Hi KK,
Changing the SIA Name:
it is not possible to change the SIA node name, you should create a new one and then create a new set of servers associated to the new SIA, once all tests confirm that the Business Objects deployment is fully functional you can delete the old one.
I would request you to follow the steps which were included in the below document.
Replicating the SAP BI 4.x Environment
Follow it from We need to create a new node in the Temp server till End.