It seems like all of the default multi-company record rules are set up so that a user can only see records from his/her company or child companies.  I imported all my data under the top-level company, which has two sub-companies.  I would like to set up the record rules such that a user from a sub-company can see records from that company or the main company.  So far, I have been unsuccessful.  I see that there is a "child_of" operator, but I haven't seen a "parent_of" operator.  I have also tried the domain "['|',('company_id','=',user.company_id.parent_id.id),('company_id','=',False)]", but that doesn't work, either.  What domain string would allow for the aforementioned access?