Found this kit on ebay to give combiner capabilities to my Siege Nightbird. She is combined with my Nova Prime with the SND Primo X-Mortis upgrade kit, Smokeout with Toyhax labels, Grindcore (from G2 Brawl), and Offroad.
Ebay! Search for Nightbird Port Upgrade. Make sure you contact the seller and tell them you want Nightbird colors, Chromia colors, or one of each!
It's important not to put any pressure fitting her toes under lip of the car with the connector attached. The tiny hinges that connect the hood to the car will break off if you try to force it! This didn't happen to my Nightbird, but did happen to Chromia.