I believe the best way to learn is to create your own courses. I learn Chinese words from lessons on memrise and like to recap them before the lesson, the only way to do that without having to sift through every single word on your one course is to have many courses so that you can quickly review the ones you need. This means that I have many courses which I don’t need to urgently review now (as the lesson was a long time ago) but still want to learn from, and having the ability to merge these courses would be great. Please add it.
It could work by adding one to the bottom of the other, allowing for the ability to copy and paste levels, having the ability to copy levels into other courses or something different.