Can you combine data from multiple series?

Hello,

I am new to InfluxDB and Grafana and am a little stuck on how to setup my series for multiple sensors. I am currently using NodeRED to send multiple parking sensors’ data to InfluxDB, and am stuck on how I should format them in my database. I currently have two different kinds of series: one where all sensors are in the same series and the device ID is how I can identify the different sensors and the other kind of a series named after the device ID.

I have been trying to display a sum of all occupied and vacant sensors, but I keep running into issues. I have tried counting the last entries from /placepod.*/, but it is not working. I have also tried using GROUP BY, but it seems like NodeRED isn’t inputting the data as tags and is doing fields instead. Here is a screenshot of my series and data:

How do you suggest that I import and display data coming from multiple parking sensors? Any suggestions are welcome! Thanks!