Hi Konata,
If you want to use only 4 infoprovider data in report then you can create new query on same multiprovider and restrict your 4 infoprovider in query so that it will shows data of those infoprovider or you can create new multiprovider and include these 4 infocube in that .
just for your information Mutiprovider does not stores data.
Regards,
Ganesh Bothe