Particle.subscribe shared with different device (login)

I share my project with my brother.
Everyone has their own login ID where their devices are stored.
I have a sketch with which I publish (particle.publish) my measurements and another that I read from the cloud (particle.subscribe).
Question Can my brother read my data via particle.subscribe? Since I don’t have much knowledge I tried the particle.publish (.,., Public) command, but he can’t read.
Is there a chance for him to see my data?

This was possible via the PUBLIC option but that has been stripped away (silently) some time ago. Currently PRIVATE and PUBLIC are exactly the same thing: all private.

Grazie Mille! @ScruffR