Different datasources per client

I need to use a different .ds.xml per client, which has a clientId.
Is it possible to do this? For example, to have the .ds.xml files in different folders, example:
1/file.ds.xml
2/file.ds.xml

where 1 and 2 are the clientIds.
But:
What would be the datasource id?
And what to put in DataSourceLoader?dataSource= ?
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