Teresa,
I well remember these discussions from many years ago in central Ohio.  I think a paralegal doing work for an attorney is covered under the attorney's policy.  But only if the attorney lists the paralegal as an employee/contract worker on their application.  In the absense of disclosure the insurer would be justified in denying coverage to the paralegal, but probably still on the hook regarding the attorney. 
If you are getting work from non-lawyers, you can't expect to piggyback on their insurance.  It may work, but I wouldn't want to count on it. Your client's E&O will take care of the purchaser, but may not shield you from a claim from the insurer.  In other words, your work is insured, but you aren't. Sleeping at night is just a lot easier with insurance.