Buying a rent controlled owner occupied building

[Charles Ng]

Need some help.  Interested in buying a rent controlled (5 unit) building in NJ.  It is currently owner occupied, owner lives in 1 unit and family members in another 2 units.  If I purchase this building,and owner and family leaves, how do they determine rent control for new tenants coming in?  Do they look for the last non family registered rent and add the appropriate increases from that base?  Thanks.