The search results do not provide specific information about the Free Syrian Army seizing a location referred to as "Center S" in 2014. However, they do mention various military actions and seizures by the Free Syrian Army during that time period. For instance, by October 2014, the army had seized Sheikh Najjar, reinforced Aleppo Central Prison, and captured Handaraat, almost besieging rebel-held Aleppo, as detailed on Wikipedia's page about the Battle of Aleppo (2012–2016). It seems that "Center S" might be a specific location or installation that isn't widely recognized by that name or it could be a miscommunication or error in the name. If you have more details or the correct name of the location, I could provide more precise information.