iTunes library and device do not match

so I have my iTunes library. It started Way back with the loading of CDs and ripping online. The library is on my pc and myself and my partner would connect to the pc and sync. So in effect have the same library.

Recently got apple Music account (family) So I have been downloading from there. either by CD or Apple Music I store all my albums by smart playlist And download by pc rather than iPhone.

So I have all these new smartplaylists from Apple Music as well as my own historical. And they show fine in my library. They actually also show on my iPhone. Happens automatically.

However when I connect my iPhone via lead to the pc and click on my device And music. The list of songs showing is massively reduced. None of the new downloads snow on it.

Cannt figure this out as the downloads are on the PC

the issues this cause is 2. Firstly when I open sonos I cannot play the songs via my playlist as “on this iPhone” has the restricted list as detailed above. So how do I get my iTunes playlist to replicate to my device in full. The second issue is when I connect my partners up the play list on the PC won’t syncs across. So they not getting the new playlists I set up.

Baffled.

And sonos isnt user friendly. I can play Apple Music. But I just cannot get what shows in iTunes on either my phone or indeed the pc to show on sonos. And it is something all tied up to the full of my iTunes not replycating to what’s on “my device“ when less connected.

Hope that makes sense and can anyone help