If you need to find posts' IDs where you have links with old member directories search you may use this snippet

Find pages with search

/**
 * Find pages that contain old link to the Members page. Search by "um_search=1"
 * @global  wpdb   $wpdb
 * @return  array  An array of posts IDs
 */
function um_find_pages_with_old_static_link_to_the_members_page() {
	global $wpdb;

  	$pages = $wpdb->get_col( "SELECT ID FROM {$wpdb->posts} WHERE post_content LIKE '%um_search=1%' AND post_status = 'publish'" );

  	return $pages;
}