Lots of conflicting reports on that. Some are denying it, some are saying it's a full hand over, others are saying they're just bringing in Syrian Border Guard units to mix into their units, thus preventing the Turks from being free to shoot. Either way, the SAA and the SDF both have a common enemy in Turkey right now, so they're gonna work together to limit the Turkish-FSA's push.
Of course, all this has put the Raqqa offensive on hold.