Pet-sitting in your home--with your pets there

Has anyone had someone else's pet stay at your house for a few days while the owners are away? How does everybody get along?

My parents are away this week and my mom made me promise to leave Shadow (the family cat) at their house as she believes coming to our house would disorient him and my kittens would make him nervous.

I think he would be fine but I have obeyed her wishes.

Has anyone ever had a new cat come over for a week? Is a bad idea? Would it be traumatic to Shadow (He is 15 years old)?

I am worried that next time they go away this winter it will snow and I won't be able to drive to their house to feed him and love him. I would love to keep him at our house for the week.

when my cat was a kitten i didn't like leaving her alone so i would drop her off at my sisters house (who has 2 cats of her own) and she was fine.. granted she was a kitten and wanted to learn what everything new was whereas my sisters cats where just like whatever leave me alone.

i guess it depends on the pet itself and how it normally reacts to new situations/people