This whole horrific plan seems to center around little Philip as the bargaining chip for whatever DW and any accomplices (if there are any) wanted. This is thinking a little outside the box but in looking at the proximity of St Albans School from their home on Woodland Drive...
https://www.google.com/maps/dir/320...8721446d01!2m2!1d-77.068678!2d38.928564?hl=en
How would DW know that little Philip was home due to the go kart accident? Maybe he didn't know. Did Philip walk to school or ride his bike? Was it customary for AS or SS to drive him to school? Could the plan have been to kidnap Philip on his way home for ransom? Wouldn't that have been much easier? After getting the money or whatever he wanted, as long as the kidnapper's identity was concealed, he could have just let Philip go. Instead, he was determined to punish the family. I do agree AS could have been targeted while she was out in her car. The time this all started is what is such a mystery. What time did St Albans school let out? If this happened before 3pm and no one came to pick up Philip from school that would have been a red herring. I suppose DW could have made AS send a text to school or, if Philip had a phone, to him saying to walk on home. AS might have refused to do so but DW could have sent a text using AS's phone. I so wish he had been in school that day. At least he would have had a chance to still be alive. Not sure if any of this makes any sense to you all. Thinking out loud.