Does conventional loan allow buying a 3 unit and carriage house?

[Plaku Mere]

I am in the process of purchasing a 4 unit property where 3 units are under one address and the carriage house is on another address. The carriage home is setup with the garage on the bottom floor and the one unit on the top. They are on the same lot and pretty much attached to each other. In the past have not have had issues purchasing 4 units with all units in different addresses but now it’s a bit different with the carriage house being in the mix. The taxes are listed only under one of the address. Wanted to look ahead if any issues can come up during underwriting. Heard from the lender that we will see how the appraisal will come? What would the appraisal have anything to do with this situation?