<?php
function my_bp_groups_forum_first_tab() {
	global $bp;

	$bp->bp_options_nav['groups']['home']['position'] = '50';
}
add_action('wp', 'my_bp_groups_forum_first_tab');
function redirect_to_forum() {
	global $bp;

	$path = clean_url( $_SERVER['REQUEST_URI'] );

	$path = apply_filters( 'bp_uri', $path );

	if ( bp_is_group_home() && strpos( $path, $bp->bp_options_nav['groups']['home']['slug'] ) === false )
		bp_core_redirect( $path . $bp->bp_options_nav['groups']['forum']['slug'] . '/' );
}
add_action( 'wp', 'redirect_to_forum' );
?>