Actually I want to use codes to EDIT sale invoice

current sale invoice is as follows

vou_no--code---Product---qty---rate--Amount
---1-------1401----Apple------10----15----150
---1-------1402----mango-----20----15----300


Now I want to edit current invoice as

vou_no--code---Product---qty---rate--Amount
---1-------1401----Apple------10----17----170
---1-------1403----Banana----30----22----660

After editing, I delete current invoice and insert new one on its place with same vou_no.