Product:SET code is:
$R.images = ($R.images || "") + "," + $value;
Video shows a trick to add same image to multiple products at once using calulated column in S‑BULK Excel Like for Shopify. Same concept is avalibe in SellingCommander for WooCommerce, Virtuemart, GCM, Facebook/Instagram Minishop, WIX Stores, Etsy
