😳*UPDATED*She wants me to add her to my credit

So one of my close friend wants to buy a house... She has bad credit and she tried paying to get it fixed but nothing is working yet. She recently asked if i can add her to my credit card so she can have good credit and get low interest for her house. Im kind of shocked and dont know if this is a good move or not? What would you do?

She said she dont mind paying me. How much would you charge? How many point (ball park) does it take out of ur credit score after running it for a house? If i add her as an authorized user does her credit automatically shows the same as mines? *She said i would keep the credit card that’s under her name so she wouldn’t use it* Any general advice?