This is my project structure;

Overall Project
│
├── backend-sub-project
│   ├── .vscode
│   │   └── launch.json
│   ├── node_modules
│   ├── src
│   │   ├── infra
│   │   │   └── stacks
│   │   └── services
│   │       ├── model
│   │       ├── monitor
│   │       ├── shared
│   │       └── spaces
│   ├── test
│   │   ├── infra
│   │   └── services
│   │       ├── monitor
│   │       └── spaces
│   │           └── handler.test.ts
│   ├── jest.config.ts
│   └── package.json
│
└── frontend-sub-project
    ├── public
    └── src
        ├── assets
        ├── components
        │   ├── model
        │   └── spaces
        └── services

Within vscode, if I open my backend sub project as a project / workspace (hope the terminology is correct) in its own right, I can debug the open file i.e. handler.test.js by hitting the Run and Debug icon on the far left.
I get asked which configuration from launch.json I want to use and everything works;

If I open the Overall Project, I CAN’T debug the open file i.e. handler.test.js by hitting the Run and Debug icon on the far left, it opens the following dialogue;

I want to keep my tests and their configuration within the sub-project, so any help would be appreciated?