I am preparing a solution for this, and would need a specification:
Has Content Type A, B, C and D to be the SAME on both Content Structures, or could it be like this:
Structure 1:
Content types A, B, C, D (Custom Post Type named A, B, C, D)
Structure 2:
Content Type A1, B1, C1, D1 (same hierarchy but different Custom Post Types, namd A1, B1, C1, D1)
Note:
On both Content Structures, the Content Types would be the exacts same (settings) but would have different names, to be detailed, alike "duplicated" Custom Post Types, but using different names + Slugs
Creating posts in Content Type A, would obviously not create posts in Content Type A1.
Since you wont link across the Content Structures, I think this could fit your needs?
In this case, the solution would be achievable with nested Views.
In the case on both Content Structures you want to sue the exactly same Custom Post Types, I need to dig deeper into it.
We need to "Differentiate" the Posts of those content types to link them accordingly
Please can you let me know if solution #1 would fit your needs?
Thank you for your collaboration and patience