To retrieve screen values while implementing BADI

Hi everyone,

I am new to solution manager. In create incident screen , The "assigned to" field is a partner determination header field . Can anyone suggest how to retrieve the field values while implementing a BADI. For the rest fields of the screen,   i have retieved it  by FM "CRM_ORDER_READ". This FM is not having the field values of the  "assigned to". How can we get the value of the field from the screen.

Please suggest me some points.

Thanks a ton in advance