Are multiScroll.js and fullPage.js compatible? Can I combine them on my website?

As it happens with PagePiling.js, multiScroll and fullPage were not designed to be merged. However, that doesn't mean that it is not possible  You can try to join them. We provide you with the required documentation to do so: the fullpage.js documentation and the multiScroll documentation

However, notice that you are on your own in this task. They are not thought to be mingled. That's why support for it is not provided in any form.