Normally you will need a separate Melissa for each of your air conditioners.
However, you can control more than one A/C with a single device, if:
- the air conditioners are in the same room
- Melissa can be placed close enough to all air conditioners, without any obstacles between the device and the A/C
- all air conditioners are the same model and/or could be controlled with one and the same remote control
Keep in mind that if you control two or more air conditioners with a single Melissa, you will be sending the same commands to all of them at the same time.