Question about randomizing sets of blocks in survey flow editor

Hello,
I hope this is an easy task: I'm trying to randomly present 9 blocks that are grouped into 3 'sets' so that a participant sees every block in the survey. Set A has 4 blocks, Set B has 3 blocks, and Set C has 2 blocks. I want to randomly present one block from each set in this order: A-B-C-A-B-C-A-B-A, showing all of the 9 blocks exactly once.
I've spent hours trying to figure this out but no luck. How would you recommend I approach this task? I haven't tried any JS, but I'd be willing to give that a shot if it's more efficient.
In addition, I wanted to include a separate prompt block before each question block (i.e., 9 prompts). The prompts and questions would have to be paired together in a fixed order (prompt block #1 → question block #1, etc.) This was more challenging and I'm willing to abandon it unless anyone here knows a solution.
Thanks, I appreciate your help!