Any steps we can take to prevent our family members from falling for the ninja van type of scams?

Just make sure you pay everything online before the item is delivered, don't do cash on delivery. Then tell your family members that your orders are always paid for already. If COD, just reject

Hi Anon! To avoid such Ninja Van type of scams, you can consider trusting messages from their telegram bot (@ninjavanbot) instead of regular SMS. Additionally, I would also keep track of my purchases so that I would not be influenced by such messages. Hope it helps!