Import this module in your Hugo config.toml.

[module]
    [[module.imports]]
        path = "github.com/basa-casa/admin-hugo"

config.yml

module:
  imports:
    - path: github.com/basa-casa/admin-hugo

config.json

{
    "module": {
        "imports": [
            {
                "path": "github.com/basa-casa/admin-hugo"
            },
        ]
    }
}

Vendor the module files for easier copying/overriding

hugo mod vendor

Copy /exampleSite/content/admin/ from all three admin modules, into your project.

Modify the cascade.config object in _index.md to reflect your project. This controls the static cms backend and other settings common to each sub-cms.