Show a DNA icon in the person box on a chart when the person’s parents have descendants with a DNA test from more than one child (line from Home person + one other) that are ICW the home person. Bold the icon or otherwise distinguish it when the user has validated that the DNA is confirming the relationship (could be from a different common ancestor couple). Provide the ability to get a list of the tested individuals who descend from the parents of the person in the chart. Provide the ability to add a note to the DNA parental confirmation for the selected person in the chart.
Getting fancy would let the user have parental confirmations from more than just the home person’s ancestors. For example, I could confirm the ancestors of my father-in-law with his DNA matches and his ICW.