Writer - embedded mail merge data source

is there a way to embed mail merge data source in a Writer document?
I have dozens of documents shared by some users working on different PC. So far, I’ve only created data sources locally for each user.

Yes, since LibreOffice 5.1 (see “Mail merge embedding of the datasource definition” in the release notes).

But maybe you mean not only the definition, but also the data itself (which would be useless, since then it’s not editable independently of the mail merge document, and defeats the whole purpose of mail merge function)?

In an Answer @Liuc1 had written this comment: (Answer deleted)

I’m using LibreOffice 6.4.7 and the source is a Access db.
In the data source registration wizard I check the option to embed the definition within the document (it’s in italian)
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but the data source is stored in the local position (that one grayed out in the wizard)

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If I try to open that document with another user on the same pc, that data source is not registered for the new user.
This happen even if I force to save the .odb file in a common shared folder on the pc.

I don’t know what’s wrong.