Look at my cousin's photo and tell me.

If you use her photo as a chat background to chat with your cousin, it's nothing, but it's not necessary to use her photo as all the chat backgrounds, which is really bad. You might as well find a beautiful picture of a beautiful star or beauty on the Internet.

If your cousin doesn't agree, you should respect her and make her unhappy, so her cousin won't have a chance to chat. Not worth it.