create-custom-tab.php

<?php
function setup_group_nav() {
	   global $bp;
	   /* Add some group subnav items */
	   $user_access = false;
	   $group_link  = '';
	if ( bp_is_active( 'groups' ) && ! empty( $bp->groups->current_group ) ) {
		$group_link  = $bp->root_domain . '/' . bp_get_groups_root_slug() . '/' . $bp->groups->current_group->slug . '/';
		$user_access = $bp->groups->current_group->user_has_access;
		bp_core_new_subnav_item(
			array(
				'name'            => __( 'Custom', 'custom' ),
				'slug'            => 'custom',
				'parent_url'      => $group_link,
				'parent_slug'     => $bp->groups->current_group->slug,
				'screen_function' => 'bp_group_custom',
				'position'        => 50,
				'user_has_access' => $user_access,
				'item_css_id'     => 'custom',
			)
		);
	}
}
	add_action( 'bp_setup_nav', 'setup_group_nav' );
 
function bp_group_custom() {
	add_action( 'bp_template_content', 'my_new_group_show_screen_content' );
	bp_core_load_template( apply_filters( 'bp_core_template_plugin', 'groups/single/plugins' ) );
}
 
function my_new_group_show_screen_content() {
	echo do_shortcode( '[bp_group_tab_shortcode type="student"]' );
}
?>