Share issues across different projects in group boards

I’m using gitlab gold and I’m trying to manage my team project management stack with gitlab. We are around 10 developers and designers divided on 4 teams. We all have independent roadmaps and different boards but we share some projects that more than one team has access to them. What I want to do is to be able to have independent board inside each team but share some issues inside a project at the same level.

An example of the organization we are currently using is:

Top level group
|
├─ Subgroup 1
├─── S_Project 1 # Only Sub1 can have issues here
├─ Subgroup 2
├─── S_Project 2 # Only Sub1 can have issues here
├─ Project 1 # Both subgroups use this project and needs to have access and issues here

At the end, we want to be able to have an epic board for each subgroup but share the issues on the project that is at the same level. Is this doable on gitlab or is there another good way of organizing it?