Paramount + App in the Apple TV+ app on my Apple TV

We are trying to utilize the Apple TV+ feature located at the top of the icons on the home screen of our Apple TV for as many of our subscriptions as possible. Since we get taken there from our HBO app and others like Paramount Plus, we thought it would be more streamlined to use one app when we can. Difficulty is that we can't sign into apps like Paramount+ and we can't find any way to do it without starting a new subscription. I decided to test out what's happening by taking the free trial offer and going through the motions. Results: I checked my subscriptions in my Apple ID on my phone and found I had two separate subscriptions for Paramount + and CBS All Access Paramount +. The second subscription is for a year. Why? My BritBox, Acorn and other subscriptions won't allow me to sign in with an existing account either. So we have to use the individual apps to access them but always end up in the Apple TV+ app with no access directly through that app. It's possible I'm not seeing the proper path but I currently can only play the next episode but can't get a new feature without starting with the individual app (like BritBox) from scratch. Any Help? Chris