Converting II (2) & B Teams into reserve teams

Hello, sorry if this isnt the correct place to post this.

I am looking for help in transforming the 2nd teams or B teams e.g. "AS Monaco 2" or "FC Bayern II" to either reserve teams or U23's similar to that of the UK or Italy.

I understand some editing of the competition rules are required, and I have experimented, but so far I have managed to convert their appearances to "Non-Professional" but not stop the fact they are assigned to the 2nd team from displaying on their playing history.

Are there any tutorials or posts detailing how to accomplish this? Apologies if I have missed something, I did look through a number of posts.

Thanks in advance.