Is it odd that it's day 4 when the FBI brings dad into the search at the park to retrace steps?
4 days later, what good would that really do to aid in the search for Maddox?
I wonder if the other adult(/adults?) who was/were with Maddox and his dad were also brought in to retrace their steps that day and if the purpose of this, on day 4, was simply to see if all adults retraced the steps the same? Because how else could that actually aid in the search at this point, several days later in terms of where he could be in that park now?