Question about batched writes

[Boarders]

In the docs here you explain how to do batched writes:
https://glean.software/docs/write/#creating-a-database-using-the-command-line

but earlier in the document it says: "It is only possible to refer to ids from facts in the same file, if you are writing multiple files using glean write or via the sendJsonBatch API."

I am wondering then how does one refer to earlier facts in a later file or if it is no longer possible to refer to such facts (perhaps it is possible by something other than the id)? What is the currently recommended way to handle a case like this?