How to change Drillthrough Defination using SDK?

[jd]

How to change Drillthrough Defination using SDK.

I created a drill through from Report Studio report to Powerpaly Studio Report using Drillthrough Defination in package level.(ex: for Chicago Region)
I have to create the same Drillthrough Defination for more than 7 Regions.
So I copied and pasted the Chicago Region Drillthrough Defination in all other Region packages. 

Here is my question: pasted Drillthrough Definations in each package is pointing to Chicago Region Source mappings. Is there any way to change the source mapping to related Region

Note: currently I am changeing them manually but it is too much wrok around. To make it simple is there any way to get it done??

Thanks in advance.