Separating heat per unit.

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I've recently purchased my 1st duplex. The previous owner had the heating (hot water) upgraded. He separated the plumbing per unit on a one boiler system. I've made the decision to have a 2nd boiler installed so my tenants are responsible for their own heating bill instead of offering heat included with the rent. My only challenge is trying to decide whether or not I should keep the entry way/star well heated. There are two 6' and one 2' radiators tied together and from there the line goes up to one room in the 2nd floor unit and  then return. Regardless, I need to break the lines somewhere. Should I to put one of the radiators on the 1st floors lines or just cut them off and let the entry way go cold in the winter? 

Any suggestions?

Thanks!!