Studying a Language from two Base Languages
I am trying to add "Learning Spanish for French Speakers". I am already in "Learning Spanish for English Speakers". Duolingo would like me to switch. Anyway to just add?
Switching really means adding. To go between base languages, you have to go through the "Add a New Course" screen every time. Your progress on each course will be saved when for when you switch back. There is a workaround somewhere that lets you switch between them more easily.
You don't actually lose your progress from English. If you switch and then switch back to Spanish from English, you will still have that course.
This is by far the best option given by Duolingo for switching between base languages.
There is a user script also available which may just do what you want. But not sure if it supports all the newly courses.