I'd like to change the name of of the tab "Related Products" in the Product Information in the Administration area (/catalog_product/edit/id/123).
I could easily do it changing the name in the code (app/code/core/Mage/Adminhtml/Block/Catalog/Product/Edit/Tabs.php) but I'd prefer to avoid changing the Magento core. So I was looking at the language files (app/locale/en_GB and app/locale/en_US), but the has no effect.
I verified the language used in the admin area is English UK (https://stackoverflow.com/a/14159348/1190011).
(Magento CE 1.9)