Prestashop modificatio on add/edit features page

i need the following modification on Prestashop 1.5.4.1: - When adding or editing a fature, select category for this feature - More then one feature can be assign to the same category - a feature can be attached to more then one category at the same time! - possibility to assign the feature to ALL CATEGORIES. - when adding/editing a product in FEATURES SECTION must be displayed only those features that are assigned for ALL CATEGORIES & for the category in which product was added. *** info: in prestashop products can be added in more then one category. Please be informed of this. This mean that if the product is added in more then one category, then in the FEATURES SECTION must be displayed only those features that are assigned for ALL CATEGORIES & for the categories in which product was added. You are free to add new table in MySQL.