Sigma-Tau owns 17%. On the merger call the Webush analyst (who knows the company extremely well) thought the agreement had something in with regards to a takeover and the license expiring after 8 years (from US approval). Also in the filing Sigma-Tau indicated some open business needed to be resolved before executing a support agreement.
JAZZ had secured 15% of the shares (though I believe the figure was low 20's when diluted shares are factored). They need to get 66% of vote (though I believe they can lower it to just a majority). IMO I don't think they can get it passed without getting Sigma-Tau on board. The easy thing would be to negotiate a deal with Sigma-Tau I would hope Sigma-Tau is considering their own bid that may be just wishful thinking on my part