I had the same problem as you, but then I figured it out and posted that clarification on page 13 of that thread. I said:
“*I looked at the Mixing Supplies section on AD. I couldn’t find any PA listing. Then I found that it’s an option when buying the 30mL bottle. However, I don’t see any such option for a To-Go bottle. I assume I would have to buy a 30ml **and an empty To-Go. Correct? *”