Is it possible to add lead time while creating Back to Back IR

Hi

Is it possible to add a processing lead time while automatically creating a Back to Back IR?

Say based on the customer request date the SSD on the customer SO is 30-jun-2015 and the transit lead time for getting the material from internal supplier is 2 days. In this case the IR is created with need by date as 28-Jun-2015. Can we add a processing time of say 1 day while calculating the IR need by date, i.e. after receiving the material from supplier the re-packaging takes 1 day. In this case the expected Need By Date on the IR should be 27-Jun.