ASG, Common Law Employee or Multiple Employer

[Zoey]

Let me set the scene...

Two separate companies (no common ownership).  Both are brokers.  Company A has two employees, other than himself.  Company B is a sole broker who performs services only for Company A.  However, due to how the "pay" is set up, he doesn't receive compensation from Company A.  He receives his commissions directly from the investment company (broker/dealer agreement).  However, the owner of Company A does have the authority to terminate him, tell him what do, and provides him an office within Company A, etc.  So, my question is this...

How would you classify this situation?  Affiliated Service Group, a Common Law Employee, or set them up as a Multiple Employer Plan...as they do want to be covered under one plan?  (My thoughts are at the very least, it would be an ASG, but I am questioning whether it could be a Common Law Employee situation.)  

Thank you in advance, for your responses.