How do you change created player pitches

I'm working on my pitching archetype in DD but I only have fastball, changeup and slider. I'd like to maybe add a sinker instead. I assume I'll get to add more pitches later on.

I believe that is done in RTTS but feel free to correct me people who actually use CAPs

It happens in bullpen practice between games in RTTS. I've was able to have 5 pitches even before getting silver archetype.