No problem, just a question: Is it possible for the user to search in only one Blog if he/she wants to? All the Blogs are activated for search as standard.
I use multisite “Blogs” for differents departments in one company
Well, there is no front-end filter for that unfortunately. On the plugin back-end, under the Multisite options panel you can choose which blogs to include the results from, but of course that cannot be changed by the user.
Perhaps creating another search instance for a local search, or searching a specific blog only could be a solution. Not the best solution, but it could work.