Golden Retriever Companion?

I've finally convinced my parents to get my 9 year old golden a companion while the kids are at school and my parents at work. But they said it would have to be a small dog so right now i have it narrowed down to a west highland white terrier and a apoo. If you could help it would be great. If you think neither of these breeds would be a good choice please list the breeds you think would be a good one. thanks.