Hi Mohan,
This is a very sensitive task. But you can finish the task safely if you follow the below steps.
1) Collect all the migration steps properly in Dev and move to Qua first
2) Change the process Chain variants by including your DTPs and move it to Qua
3) Run all your DTPs with "No Data Transfer, Delta fetched" in execution tab. This will ensure all delta requests have been uploaded further into your Infoproviders. This is the key step to make sure your current delta mechanism does not get affected in Qua and in Prod too.
4) Run your process chain in Qua to make sure all DTPs picking normal delta and no data duplication happening in the infoprovider level
5) Test properly in Qua and move the same transport requests from Dev to Prod and repeat Steps from 2 to 4 in prod
Hence, your regular delta will not be affected and the situation will be cool.
Regards,
Suman