I am starting again the thread of this issue concerning LMS and deezer app.
With family option, we can have up to 6 different profiles.
LMS works only with the main profile (email address and password).
I can access to my profile by "friends" but it is not the quicker way to listen music.

Regarding Deezer API, it is possible to access to the profile by adding the user in the url for each request (like a folder).

Do you know if a patch is possible for deezer (by adding a field user) ?