I’m doing it right now from 1 document to 200 documents
If it’s a 1 way sync the best way to do it is through a webhook pack. Here’s my personal favorite
And here’s a quick tutorial on how to use it and how to actually send the data over
If you’re looking for a two way sync (so that the data will write BACK to the main document) your best way, in my opinion, is the 2 way sync pack discussed here