If you activate PHP Module in your 1&1 Managed Server settings, you will not be able to use your own php.ini. As an alternative, the values to be changed in the php.ini can be written into an .htaccess file.
Example for view of the php.ini:
magic_quotes_gpc = off
Example for view of .htaccess
php_flag magic_quotes_gpc off
For additional information, you may want to reference: