How to present again the questions that the randomizer has "selected"?

Hi!,
I am running a survey with three parts.
1) The randomizer selects 4 out of 200 blocks (each block with 4 questions and a couple of pages).
2) I provide training to participants and then ask them to complete a quiz.
3) I want participants to answer the same 4 blocks presented in 1) (randomly selected by the randomizer).

My problem is that I don't know how to keep track of the blocks/questions that the randomizer has chosen and how to show them again.
I am updating a .txt file with all the questions and blocks, trying to automate everything. I'm not sure whether I can use logic, as I have 200 blocks... Also, I think this is the only option I have since I can't create part 2 with the .txt.
Any ideas? Embedded Data? Piped text? Javascript? Loop and Merge? Ideally I should be able to solve this by uploading a .txt or by minimizing as much as possible the manual work. I could manually create a couple of conditions, but not hundreds.
Can anyone help me please? Thank you!!