Thanks to https://adrianshort.org/create-multiple-forks-of-a-github-repo/ for the instructions.

In summary (using Telescope, an open-sourced project on Github, as an example):

1. git clone https://github.com/TelescopeJS/Telescope.git cb2

2. git remote rename origin upstream

3. git remote add origin https://github.com/lpatmo/cb2.git

4. git push -u origin master