Echoes of Family Lost

Alive!  After four years believing her older sister lost and presumed dead in the horrible Breakup of the United States, Lily Barrett gets word from her dear friend, Ai - and Ai's family of Machine Civilization - that Callie Barrett is very likely alive. but over 900 miles away in Knoxville. Using the resources of her and Ai's family, Lily puts together a search party to go find Callie:  old, broken, and burnt Orloff - an expert in surviving in the Badlands, Ai's little sister, Fausta - her machine mind controlling a Combat Android to protect her friend, all together in a cart pulled by their sturdy pony, Clyde. It's almost a thousand miles to go, with something very odd trying to limit their ability to communicate over distance and even to cross bridges.
 A chance meeting along the way in Huntsville, former Alabama, wrecks their plans, and puts all of their lives in danger.