RBBM and changed two words in your post which are blue.
I disagree with the bolded part - I do not think SP "cared" for the other occupants. If this was a planned murder, the SP is a highly organized type who had a detailed plan which likely included Plan B variables. Other occupants of a house are obstacles, threats, interference, persons who can dial 911, extra persons to disable or murder if necessary, noisemakers, "you cannot herd cats" and one occupant may run to a neighbor, there may be a dog, and, a victim has an advantage in their own home because they know the space intimately, for example where a gun is hidden. The CoC space elimates all of these issues and more, and gave the advantage to SP who controlled that space. JMO, not bashing you or your post, I just disagree that this SP cared about anybody, and to me, SP's actions were very mission-oriented, operational, an op. I do agree with you that if there are more persons involved in a conspiracy that those persons may care about the family.