Multifamily with one main heat control? suggestions

[Nicholas R Paust]

Hello,

I wanted to know what others did in this situation.  I'm under agreement for a 2 unit multifamily house.  The house has unit 1 on the entire first floor and unit 2 occupies the second and third floor.  Unit 1 has the thermostat that controls the gas heat for unit 1 and just the first floor of unit 2.  Unit 2 on the third floor has window units for heat/ac.  I'm wondering what I can do at this point?  Do I just put a lock on the nest thermostat an control the heat myself and deal with the tenants if its to hot or cold?  Do I just have unit 1 pay the gas? which means unit 2 has to just rely on the electric windows units for comfort?  I thought about just blocking the vents on the second floor, but it can mess up the air handler if I reduce the CFM its meant for? I'm open to suggestions