The attitudes of JS' mother and sister go in line with my ongoing suspicion that JS may have handed them off alive to someone (friend, relative, trucker).
Also, his apparent controlling behavior and his game-playing with LE/FBI (the lies, the wild goose chase search tips)...
I still haven't seen a solid MSM article with a quote from LE that he admitted to killing them (just "according to sources, Police Chief Weeks said...").
With all the training of LE, FBI, mental health professionals...is it possible that he could pull off a lie that he killed them (if he said that)?
speculation:
Could the boys be alive? Maybe he thinks that would be the second best way to torture TS...for her (and almost everyone else) to believe the boys are dead but not found. Meanwhile they are alive and would go on to live their lives hidden somewhere until discovered, or old enough to either escape or be on their own. Then they might seek out help and maybe their maternal side of the family.
IF he had handed them off...I would hope that it was to someone who would raise them in a loving home and community. But I have zero confidence that he was capable of making such a good choice. And, of course, IMO, he had no moral or legal right to do such.
It is difficult to come up with a best-case scenario within the confines of what info has been released.