Hi Amit
As far as I know .. check the webdynpro component it belongs to and then using SE80 you can create a webdynpro modification ..
The Webdynpro component would be something like /SAPSRM/WDC_SUCO_SREG*
You may also want to have a look at these notes
2024263 - Restrictions in transferring address information from ROS to ECC
1848510 - Enhancement of the ROS registration screen with customer fields
There are restrictions to the ROS screen ..
Let me know if that helps
Regards
Vinita