Need help burying a Yelp Review

I been doing local SEO for a couple of months and now have my first client asking for reputation management. They currently have 1 negative review on Yelp which is about 2 years old that they want buried.

The owner had friends and family post reviews over the course of 2 years to try to knock it down, but all the reviews are filtered except for the negative review.

I explained to him that the other reviews were probably filtered because either they came from the same IP, or are from newly registered accounts that solely posted a review on his page.

What would be the best practice to get positive reviews to stick and ultimately push down the negative review?

I'm thinking I would like to hire someone to post real reviews that I'll capture from real customers on aged, profile completed, California based yelp accounts posted on a set interval. Anyone here offer that sort of service? PM me.

I know my second strategy would be to build web 2.0 sites and apply SEO to try to outrank the Yelp page off first page of Google.

Any other suggestions, please let me know.

One other thing is that the owner posted a reply to the complaint. To my understanding that will make it even harder to bury, correct?

Then have him reply to a positive comment.

Your best bet: Build up sites above it, and cover it with legitimate reviews.
We can't speak of Negative SEO so I won't go there.