How to *fork* shared-theme-assets?

I wonder if update a forked shared-theme-assets package within npm and then chose it from config.json on custom theme is razonable for that custom mod.

*I’m editing a shared dropdown function used by burger-menu (to enable it on >992px viewport instead >768px):

function dropdown() {
    const mediaQuery = window.matchMedia('(max-width: 767px)');

How to modify that function without touching shared-theme-assets?

Perhaps it can be done in a more elegant way? :)