I've trying to change the login link /wp-admin to custom. But it should be done when the client agrees with it in Dashboard panel. I've used ACF Pro, create a checkbox in Theme Options. There is a question: "Do you want to change the wp-admin link?" If client checked "Yes" -> click Save Changes then the new file should upload to WordPress root near wp-login.php file. My file is placed in wp-content/themes/mytheme/ folder.
Have any ideas?
P.S. Sorry for my bad English.