WordPress at a glance
function is not described

add_blog_option() WP 3.0.0

Add a new option for a given blog id.

You do not need to serialize values. If the value needs to be serialized, then it will be serialized before it is inserted into the database. Remember, resources can not be serialized or added as an option.

You can create options without values and then update the values later. Existing options will not be updated and checks are performed to ensure that you aren't adding a protected WordPress option. Care should be taken to not name options the same as the ones which are protected.

No Hooks.

Return

true/false. False if option was not added and true if option was added.

Usage

add_blog_option( $id, $option, $value );
$id(int) (required)
A blog ID. Can be null to refer to the current blog.
$option(string) (required)
Name of option to add. Expected to not be SQL-escaped.
$value(mixed) (required)
Option value, can be anything. Expected to not be SQL-escaped.

Code of add blog option: wp-includes/ms-blogs.php VER 5.0.3

<?php
function add_blog_option( $id, $option, $value ) {
	$id = (int) $id;

	if ( empty( $id ) )
		$id = get_current_blog_id();

	if ( get_current_blog_id() == $id )
		return add_option( $option, $value );

	switch_to_blog( $id );
	$return = add_option( $option, $value );
	restore_current_blog();

	return $return;
}