Not able to fix the cooling system

My dad and I are buying a triplex together as an investment.  Well, my dad is buying the investment. However, it will be my handyman skills that will be getting this triplex fixed up and leased.  Closing is on Wednesday, and by Monday our wrecking crew will be on site to start the demo process. we will try to save as much of the original structure as possible, but we definitely have our work cut out for us.  I am a Heating, Ventilation, and A/C technician by profession, and a manager of a nearby HVAC company. I’ve been in various different construction jobs for the last 20 years, always coming back to HVAC work. I can see that the current Heating, Ventilation, and A/C system installed in the triplex is not only old, it isn’t even close to the proper size requirements for the square footage of this triplex.  The heating and cooling system is undersized, and it was from the start. I met several of the renters already and I can understand why the 3rd floor renter complained about the heat. Even worse, there is only one thermostat between the 3 units. So I promised them that when we start the remodel, that I would make sure that all the units would have their own thermostat. I’ve already decided that the ductless mini-split Heating, Ventilation, and A/C system would be the best Heating, Ventilation, and A/C technology for this type of property.  

ac zone control