Custom Two-PDF Column Merge -- 3

I have 2 PDFs whose columns need to be stitched together into one document. The finished file must read left-to-right with every column from the Level2 pdf appearing first (with 2 columns (Concept focus and concept analysis columns merged) , followed immediately by the corresponding column from the Level3 PDF.

Nothing in either source should be reformatted: font, size, spacing and line breaks all stay exactly as they are. I only need the columns combined in the custom sequence described above.

Deliverables are simple:
• A single, page-for-page merged PDF that respects the original formatting.
• The editable working file (Acrobat project, InDesign file, etc.) so I can adjust later if needed.
In this format
==================
Question X
[Columns from Level2 - (Conceptual focus + Conceptual analysis in single column as Conceptual Analysis) + Examiner’s Likely
Focus] [Columns from Level3]
Question Y
[Columns from Level2 - (Conceptual focus + Conceptual analysis in single column as Conceptual Analysis) + Examiner’s Likely
Focus] [Columns from Level3]
====================
In total
Question X
5 columns

Add UPSC Prelims Blueprint to the start of PDF according to topic and then Level4 pages
Suppose we have polity of Level2, Level3, Level4
Then final Polity pdf should have
UPSC Prelims Blueprint for Polity + Level4-Prelims-Polity + (Questions in given format)
Finally there should be 11 booklets of different subjects
Let me know your estimated turnaround time and any checkpoints you’d like for quality assurance.