You cannot create a player and simply "inject" them into an existing BAL save. You must create the player first, then start a new career.
, as it lacks comprehensive built-in customization for certain features like starting stats or specific team placement. Third-Party Legend Editors
Most BAL editors for PES 2010 focus on providing total control over the development of your "Legend":
The is a popular third-party modification tool that allows players to bypass the slow, organic growth system of the game's career mode. While PES 2010 offers a native "Appearance Settings" menu for basic edits like hair or boots, the BAL Editor provides deep-level access to a player's core identity and performance. Core Features of the Editor