I agree with Smooth Operators post (#648) above assuming the older children were raised by kind loving parents who taught their children the basics - lying, stealing, hurting people or animals, etc.
I know from first hand experience that a 9 year old who grows up in an abusive household learns very young when to keep their mouth shut. And IF this had been planned, the children were drilled many times of what to say and they have it down pat.
But that's assuming this was a PLANNED MURDER OR SELLING OF Aliayah.. And that I am just not anywhere near ready to jump on that bandwagon(not saying there is one..lol.. Just using as a figure of speech).. But you say in going with it being planned it wouldve been drilled in their head.. But one has to believe it was planned IMO to get to a fabricated cover being drilled in not one, but two children's heads..
There are people whose jobs are specifically what happens in a case such as this in talking to children who have likely beared witness to some pretty horrific things.. This is what these individuals do and it is these children who have been raised in dysfunction beyond belief and abuse the likes of most of us can't comprehend and it is specifically those exact dysfunctions/abuses that have brought the children to have crossed paths with these specifically trained individuals that do not come into play until something horrific and criminal in nature has taken place..
These individuals largely and for the most part do not deal with children who come from loving, stable, disciplining, and intact homes.. But rather the vast majority of children these individuals work with, counsel, help are children who come from homes identical to the Lunsford home and some much, much worse.. The children have crossed paths with these professionals strictly because someone in their home has done something horrific or something horrific has been done to someone in that home.. That is why the child(or children in this case) are being helped by these particular counselors, social workers, psychiatrists/psychologists..
And these ^above^ named counselors are trained in dealing with these exact type of children who do not come from wonderful, loving homes..
So, in knowing that I do not agree that it's easy for such a child to be able to effectively lie and decieve such professionals who are knowledgable and likely expecting these possible manipulations and deceit passed down and threatened upon the children they are working with..
With that said I believe that it being two children and not just one makes it all the more likely the truth("if" threatened and manipulated to have been buried and replaced with complete fabrications.. Which jmo but I don't believe that to necessarily be present in this case).. The truth would be not difficult to obtain from these children.. All done in a very precise and highly trained of methods that will do it's best to protect the child(ren) from further harm than what has already been done by the parent(s) .. But always in there being more than one child possibly holding knowledge of their siblings death or abuse the likelihood is very great IMO that the highly trained individuals working with them would be able to get to the truth from one or both.. Or ATLEAST enough of the truth to determine what has occurred to the younger sibling..
Jmo, tho and combined with the little that I know from my sister who is a psychologist that for a good piece of her career worked specifically with these exact type children who came from monstrous homes of abuse and addiction.. Tho, she was not on the criminal side but rather in private practice..