Phone + PhoneApp + TVS required to work

Hi,  I was hopeful that having setup Tailwind to work with 3 TVS sensors that I could just put the 2nd and 3rd sensors in other family cars and have them just work with Tailwind for opening and closing the single garage door.  For instance when 1 sensor leave the proximity of the Tailwind controller.   However, from what I can tell to make this all work you must have:

1. iPhone per user/car. 
2. iPhone Tailwind APP on and running at least in the background.  I'm not sure yet if I actually have to have eyeballs on the Tailwind APP.  Can the Tailwind APP be running in the background and still work properly? 
3. TVS sensor in each car. 
4. All 3 setup to work with the controller. 

My problem will be and is getting the family members to keep some "odd" app open/backgrounded on their phones.    Thoughts / clarifications?