Hi Deepak,
We have also having similar kind of requirement.To achive this you need to first change your DTP In semantic group you need to tick Visit id menas on based on this key you unique records will come in to one source package based on semantic key..some times it will come in diffrent source package thats why we nee to do this setting to avoid same key combination in diffrent package.
after that loop at your source pacakge
use AT NEW Visit id statement in code and modify your key figure to 1.it will update 1for every new record visit Id in this way you will achive your requirement.
hope it will help.
Regards,
Ganesh Bothe