My sister booked a hotel for me, and I let my friends stay, but I don't want my sister to know. If my sister calls the hotel front desk, will she tell him?

What is your concept of keeping your friend alive? If your sister has opened a room, you take the room card, you give the room card to your friend, and he enters the room by himself. The hotel doesn't know about your friend. How can you tell your sister? Similarly, if your ID card is registered when you check in, you can turn around and give your friend the door card, and he will enter the room directly without the hotel knowing.