I asked the ChatAI about how to set up a 2-beat pickup measure. It said to set the first bar as 2/4, which I did. Next bar is back to 4/4. However, I want A13 on beat 1, and A13(b9) on beat 2. It won't do it. Just does A13 on both beats. What to do?

Can you just use "Edit Riff" in the Tracks view and move some notes to bar 0 then generate up a new section from where you moved it from.
You should be able to select bar 0 then do a partial regen but it's not working yet.

I'm not following. Come again?

BiaB is weird when it comes to things like this. It will show you 2/4 but with 4 chord spaces! The trick is only the first two beats are active. Thus you must input you chords like this: A13,A13b9.

I hope this helps and good luck.

I noticed that. And, yes, I did enter it like that, but regenerating still didn't add the altered tensions in the chord. Just vanilla A13 chord.

I C. Can I do that with all of the tracks at once? The whole band is supposed to kick those chords.

The chances of the RealTracks having an A13 chord let alone an A13b9 is slim same if you used A. A13..,A13b9.. you would not have that in the Shots n Holds.
If you use midi you can get what you want.

Entering A13b9 later in the tune works out fine. However, entering it as a one beat held chord goes back to A13 with no b9. I guess I'm going to try Editable Real Tracks to see if I can just add in the missing note.

I used Editable Real Tracks and step entered the chord voicing that I want on the instruments that I want. Now the problem is that the two held chords, A13 and A13b9, are quite a bit louder than the rest of the track. I fixed that for the intro, which is a 2/4 bar, by changing the volume for all instruments in Bar Settings to -20.

However, this chord hit happens later in the tune, which is in 4/4. The A13... A13b9 hits come on beats 3 and 4 within the song(this happens a few times. How do I change the volume on all of the instruments at just beats 3 and 4?

You have a Vol adjust for the Playable RealTrack notes and you have the Velocity at the bottom that you can use Shift and drag all down. You also have Master Vol Automation in Audio Edit Master.