function bbp_add_group_id_to_forum( $forum_id = 0, $group_id = 0 ) {

	// Validate forum_id
	$forum_id = bbp_get_forum_id( $forum_id );

	// Use current group if none is set
	if ( empty( $group_id ) ) {
		$group_id = bp_get_current_group_id();
	}

	// Get current group IDs
	$group_ids = bbp_get_forum_group_ids( $forum_id );

	// Maybe update the groups forums
	if ( ! in_array( $group_id, $group_ids, true ) ) {
		$group_ids[] = $group_id;
		return bbp_update_forum_group_ids( $forum_id, $group_ids );
	}
}