force real name on register

Hope it help: https://www.jfarthing.com/development/theme-my-login/adding-extra-registration-fields/

many thanks that looks spot on

ok have started but can not find the file
theme-my-login-custom.php.

do i need to copy this from somewhere or rename the
theme-my-login.php. file then edit it?

As the info: https://www.jfarthing.com/development/theme-my-login/using-theme-my-login-custom-php/ the directory is /wp-content/plugins

many thanks blackstar all sorted with your help