Pass screen field value to search help exit for custom field

Hi,

  I have created a search help for a custom field (created in confirmation at item level) using search help exit. In the search help exit, I need to read the partner number for plant from the partner overview screen of confirmation, and pass that partner number to the search help exit of custom field created on item basic data sreen in CONFIRMATION transaction. The reason being, in the hit list, I would like to show only the custom field values related to the plant that exists on that document. It would be great if I can get some help on this.

Thanks,

Krupa