I know how you feel. I always worry when I take Max and Abbie places because I'm afraid of what they will do. If Lexi pees or poops somewhere other than on the wee-wee pads just make sure you have stuff to clean it up. If his mom gets upset, then she gets upset (unfortunately). It's not like you are going to make her pick up after Lexi. And who knows-Lexi may surprise you and be a good girl all weekend
Also, I don't think she'll scratch the leather couch. I have a leather couch and chair and it's really soft leather (seems like it would scratch easily.) Max and Abbie climb all over them and even sometimes Max starts digging on the leather and tries to bury his toys
but even then there are no scratches. Try not to worry too much and have a great time
