Multiple _id for same document or document alias

Is it possible to have multiple ids for the same document or have a alias to a document?
Already found this topic but a long time ago, checking if it was implemented meanwhile.
The use case:
I have a sql database with multiple tables with unique ids but referencing one global table which has the metadata. I would like to import the id from the global table and its metadata, but also import the metadata from the other tables. Instead of importing the same data multiple times because it's the same source, would it be possible to reference the document with the metadata?
Also, I'm getting by document _id and not by a search query, that's why I was looking for multiple document _id or document alias maybe.

You can have multiple fields with those ids, but you would need to find those documents using a search query, not by the _id.

You can have only one _id per document.

Alright, got it, thank you.