"Core Health Insurance" is a specific brand of insurance just as "Kaiser HMO" is a different brand name. The two are different and mutually exclusive. In other words, the way your question is asked would be similar to saying "Can I get a Honda Civic through a Ford Mustang?" So obviously this wording doesn't make sense.
You might have meant to ask whether the REALTORS association has a selling agreement with Kaiser. The answer is no; and there would likely be no business reason for either the association, Kaiser or the members for doing so. The REALTOR association, like most other professional associations, focuses on member benefits that provide revenue to the association while making an attractive offering to the individual members.
I stumbled onto this question because I am writing a “Core Health Insurance Revisited” article for the Freedom Benefits health insurance exchange following changes introduced during this period of health insurance reform. These other resources are available on the www.FreedomBenefits.net Web site.
Freedombenefits.net, specifically the new article at http://freedombenefits.net/affordable-health-insurance-articles/Core-Health-Insurance-revisited.html