How do you change created player pitches

[Kevin-Ate-Nine]

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.

[wynsanity318_PSN]

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

[BigFes902_PSN]

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