Upload all files listed in another file?

I’m putting together a web interface for one of our genomics pipelines. The one piece of data required to run the tool is a metadata file that contains, among other things, paths to fastq files for individual samples.

What I’d like to do is have a single dcc.Upload element that takes the metadata file, and then in another callback, upload all of the relevant fastq files in one batch. These metadata files can contain hundreds of rows so it’s not feasible to have the user manually add each one. An “is it ok to upload these other files?” dialog box would be acceptable.

My first idea was to have a hidden dcc.Upload element whose children I could populate with the files I want in another callback, but I’ve yet to get that working and suspect it probably won’t - I’m no web developer but I assume “don’t let the website I’m using grab files from my local filesystem without giving it explicit permission” is a mostly solved problem.

Does this sound doable?