In EnergyPlus, one workaround would involve plotting the hourly conditions (temperature and humidity) from the node you have highlighted to create custom hourly temperature/humidity schedules.

You could then set the 'Inlet Air Configuration' field of the heat pump to 'Schedule' and select the appropriate schedules in the fields 'Inlet Air Temperature Schedule Name' and 'Inlet Air Humidity Schedule Name'. This will allow you to define custom, hourly conditions for the heat pump evaporator coil.

The hourly schedules could be processed to include a mixture of outdoor air and exhaust from the specified air node as needed.

Currently, I see only the option of an (approximate) EMS solution:

Starting with current heating load, one would have to calculate required air flow for the air-to-water heatpump. This however depends on performance curves of heatpump (depending on air side temperatures, and maybe also humidities as well as water side inlet and outlet temperatures). Now the temperature of the supply air will depend on how much exhaust airflow is available for mixing with outdoor air.

These kind of calculations are however not at all trivial. It would probably require to imitate EnergyPlus algorithms to achieve accurate results.

If someone can come up with better recommendations, you are welcome !