Update Sale Order Header Text through Enhancement

Hi Experts,

I Have a requirement to update the sale order Header Text , when the sale order is opened in VA02 and saved.

Here in I tried using edit_text, it updates sale order header text directly in DB during run time even before the save action is completed.

But I need to just fill the header text and that has to be saved during the save action only.

I tried coding the same in the user exit (userexit_save_document) but this user exit gets triggered only when there is some changes made to the document when opened in VA02 & Saved.

Is there any user exist to pass sale Order Header text and save when save button is clicked irrespective of the document been changed or not.

Thanks in advance

Sathish