I cannot help you with an expert, however, if you are not aware of some resources regarding this group, this web site www.carlstevens.org
has a lot of information on Greater Grace World Outreach, from various sources and is mostly factual, though it does carry opinion that seems bias against the group. It has things such as court reports, numerous newspaper articles, ex-members, counter cult groups, reports from Christian organizations.
I am seeking to learn and would like to start an objective discussion on this group, that is why I cam to this forum and saw your posting. I can appreciate if you do not want to enter into a discussion on a forum in that you are involved in a court case, I can start a new thread and hope others will join that.