Jordan Edwards' death last year sparked outrage in North Texas and drew national attention.
A citizenship application for 4-year-old Angela Becerra was denied without explanation, her parents say.
Bruce Hipkins was arrested on numerous charges, including kidnapping, police said.
A 3-year-old boy with a medical condition remains missing. Five adults, including three believed to be the children's mothers, are facing child abuse charges, a third-degree felony.
Investigators believe Tristan Beaudette's two daughters, ages 2 and 4, were inside the same tent when the shooting occurred at Malibu Creek State Park.
“Like dominoes, kids started throwing up,” Highlands County Public Safety Director Marc Bashoor said of the incident.
A judge ruled Thursday that David and Louise Turpin will go to trial for what prosecutors say was a years-long abuse of their children.
Rules put in place to prevent inappropriate contact with teenage migrants might have been mistakenly applied to very young children, former administration officials say.
"She didn't have her mother, and none of us can fix that,” Dr. Colleen Kraft said of a little girl who was crying when she visited a Texas shelter.
Sydney Darnell, 12, died after suffering a gunshot wound to the head, police said.