customscript page:

at the top of the class add: private $db_connectionSecond = null;
like this:

class customList {

    private $db_connection = null;
    private $db_connectionSecond = null;

    public $auctionmessages = array();


======================================


add this function at line 60 after the first connection function

    private function databaseConnectionSecond(){ //database connection
        if ($this->db_connectionSecond != null) {
            return true;
        } else {
            try {
                $this->db_connectionSecond = new PDO('mysql:host='. DB_HOST2 .';dbname='. DB_NAME2 . ';charset=utf8', DB_USER2, DB_PASSWORD2);
                if($this->debugging == 1){
                    $this->db_connectionSecond->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
                    $this->db_connectionSecond->setAttribute(PDO::ATTR_EMULATE_PREPARES, false); //debugging
                }
                return true;
            } catch (PDOException $e) {
                $this->auctionmessages[] = $e->getMessage();
            }
        }
        return false;
    }


========================

at line 360
replace checkPaymentParams function with this updated  version:

    public function checkPaymentParams($uid = NULL){
        if($uid == NULL){
            if(isset($_GET['auctionid'], $_GET['uid'])){
                $auctionid = $_GET['auctionid'];
                $auctionauthkey = $this->getSettings($auctionid, 'authkey');
                if($auctionauthkey != false && $auctionauthkey == $_GET['uid']){
                    $post_title = $this->getSettings($auctionid, 'gettitle');
                    $image1 = $this->get_post_meta($auctionid, 'wdm-image-1', true);
                    $description = $this->getSettings($auctionid, 'getpost2');

                    $getlastbid = $this->db_connection->prepare("SELECT bid, name FROM wp_wdm_bidders WHERE auction_id = :idvar ORDER BY bid DESC");
                    $getlastbid->bindValue(':idvar', $auctionid, PDO::PARAM_INT);
                    $getlastbid->execute();
                    $result = $getlastbid->fetch(PDO::FETCH_ASSOC);
                    if($getlastbid->rowcount() == 1){
                        $formdata = array("title" => $post_title
                            , "auctionid" => $auctionid
                            , "price" => $result['bid']
                            , "image" => $image1
                            , "description" => $description
                            , "username" => $result['name']);
                        return $formdata;
                    }
                }
            }
            if(isset($_POST['auctionid'], $_POST['uid'])){
                $auctionid = $_POST['auctionid'];
                $auctionauthkey = $this->getSettings($auctionid, 'authkey');
                if($auctionauthkey != false && $auctionauthkey == $_POST['uid']){
                    $getlastbid = $this->db_connection->prepare("SELECT bid, name FROM wp_wdm_bidders WHERE auction_id = :idvar ORDER BY bid DESC");
                    $getlastbid->bindValue(':idvar', $auctionid, PDO::PARAM_INT);
                    $getlastbid->execute();
                    $result = $getlastbid->fetch(PDO::FETCH_ASSOC);
                    if($getlastbid->rowcount() == 1){
                        return $result = array("price" => $result['bid'], "name" => $result['name']);
                    }
                }
            }
            if(isset($_GET['uid'], $_GET['prod'])){
                $auctionid = $_GET['prod'];
                $auctionauthkey = $this->getSettings($auctionid, 'authkey');
                if($auctionauthkey != false && $auctionauthkey == $_GET['uid']){
                    $getlastbid = $this->db_connection->prepare("SELECT bid, name FROM wp_wdm_bidders WHERE auction_id = :idvar ORDER BY bid DESC");
                    $getlastbid->bindValue(':idvar', $auctionid, PDO::PARAM_INT);
                    $getlastbid->execute();
                    $result = $getlastbid->fetch(PDO::FETCH_ASSOC);
                    if($getlastbid->rowcount() == 1){
                        $itemname = $this->getSettings($auctionid, 'gettitle');
                        return $result = array("price" => $result['bid'], "name" => $result['name'], 'itemname' => $itemname);
                    }
                }
            }
        }else{
            $auctionauthkey = $this->getSettings($uid, 'authkey');
            if($auctionauthkey != false){
                return "auctionpayment.php?auctionid=".$uid."&uid=".$auctionauthkey;
            }
        }
        return false;
    }



================================

on line 128 (the only thing that changes is the word $this->db_connection to $this->db_connectionSecond)
change this:

 $set_new_donation = $this->db_connection->prepare("INSERT INTO

to this:

 $set_new_donation = $this->db_connectionSecond->prepare("INSERT INTO