The caregivers

Eric, a registered nurse who works with children afflicted with complex medical disabilities, attends to his adopted son Zachary, right, who is wheelchair-bound after being born with cerebral palsy, while Eric’s partner Dennis, left rear, trims the Christmas tree at their family home in Springfield, Mass., Dec. 12, 2015.

“It’s just kind of like a well-oiled machine,” said Eric. “The key for us is routine. Everything is routine.”

But routine only goes so far for the couple and their children, Zachary, 8, who has epilepsy and cerebral palsy; Tyler, 7, who has brain damage and autism; Jayden, 5, who has post-traumatic stress disorder and borderline behavior problems; and biological siblings Ryan and Mandie, 7 and 6, who both have PTSD.