Combined Templates Support

I'm creating some templates for application types I use often.

It would be cool if it were possible to combine templates.

A concrete example (sorry for the terrible "markdown art")

let's assume I have the following templates:
- tests-lib
- grpc-server-app
- web-api-app

I would love being able to create templates like
- grpc-server
- /solution.sln
- src/
- Directory.Build.props
- [grpc-server-app] (params)
- tests/
- Directory.Build.props
- [tests-lib] (params)
- web-api
- /solution.sln
- src/
- Directory.Build.props
- [web-api-app] (params)
- tests/
- Directory.Build.props
- [tests-lib] (params)

and so on...

It would be up to the root "template" to fetch and dispatch all needed parameters to the "sub" templates