I have a function in one 'parent' file that calls functions in 10 different 'child' files, all of which
I don't think it really makes a difference. Packages are cached (see https://nodejs.org/api/modules.html#modules_caching).
In my opinion, if you require them for each file versus pass them as params depends on how you want to use the child functions. If you may want to utilize the child function outside of the parent at some point, it would be better to require the needed packages in each child. On the other hand, you may have a scenario where you want to call the child function with a param that might change (for instance, you want to pass a sorting function to the child). In that case, a param would be good so you can reuse the bulk of the code.