Add support for YITH WooCommerce Multi Vendors

ordernumbers_woocommerce.php

@@ -262,6 +262,15 @@ class OpenToolsOrdernumbers extends OpenToolsOrdernumbersBasic {
 					$vendors[] = $vendor->ID;
 				}
 			}
+			
+			// "YITH WooCommerce Multi Vendor" support (vendors stored in its own taxonomy)
+			if (function_exists("yith_get_vendor")) {
+				$vendor = yith_get_vendor($p->id, 'product');
+				if ($vendor->is_valid()) {
+					$vendors[] = $vendor->slug;
+					$vendors[] = $vendor->term_id;
+				}
+			}
 			// END THIRD-PARTY SUPPORT
 		}
 		$reps["[skus]"] = array_keys($skus);