Can Visual Studio be made to debug child processes like WinDBG?

Not possible (AFAIK, any many others...) but you have several workarounds:

  1. Use this macro, it comes from the Chrome team which need to deal with a lot of child processes debugging.
  2. Put your child process on Image Execution Options so that they will automatclly open in a debugger. Then select the current active instance of Visual Studio.

There is now a power tool that lets you attach to child process: Introducing The Child Process Debugging Power Tool

Child process debugging menu