Adding an attribute

Hello, I was just wondering if there is a way I could add an attribute to device_tracker called “Requested” since I am using it for a car and just display that attribute in a group in my frontend.

The idea is I am using IBeacon to track my vehicles and I would like to have the ability to request a car (I use this with my brother) but can’t find the way to display in the front end if a card is requested or not)
Thank you!.