Client has a domain almost identical to another local business

I am helping a client who chose a not great domain name. She chose a very popular name for her line of business and then picked something available, not thinking about the competition.

For example her business name is "Popular Idea." popularidea dot com (and many other TLDs) are already taken, she has popularideapdx dot com and a local competitor has popularideaspdx dot com. It was confusing even for me.

Her website is a few years old and I know she's not open to changing her domain. How can we differentiate the two? Change her tagline? Any other ideas?