GIO_2008, everyone is saying different things, because every case is different. to be honest even if there is a law, there are always exceptions... So let's say the law states: you have to work with your first sponsor at least for 1 year in order to be able to change the sponsor.. but.. soooo many cases when the person worked much less than 1 year, and was able to change the sponsorship with no any problem whatsoever.. and other way around.... so there is a law, and 1001 exceptions and 'specials cases' for this law.. and also as SAMI_X sais, new law are coming out every once in a while... even the highly professional person sometimes gets lost.. yesterday the penalty for overstay on business visa was QR 500 per day, today they had to pay and it turned out to be only QR200 per day.. the rule has been changed… 4 hours ago!!
'go figure'.. :)
so the best way: GO AND DO IT, and THEN you will know what is the rule for YOU.

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“You become responsible forever for what you have tamed”. Antoine de Saint-Exupéry