wt
This is JMO, but I think for AW it may have been for money. I have this theory (my own pure speculation) that AW was not going to be provided for financially by the W estate after FW died. I wrote a post a while back about generation skipping trusts, and if anyone really needed one, IMO, FW and her husband really needed one with respect to the unique challenges posed by both Billy and AW.
JMO, I don't see Billy's parents thinking it would be wise to allow Billy to inherit a big chunk of anything. He failed to launch and at a minimum, he was irresponsible. And then there is AW. If they gave Billy a lot, he could die before AW, or she could divorce Billy after he received an inheritance and she could get her hands on FW's assets and blow through it all. When people who have estates (does not even have to be that large of an estate) have concerns like this, they sometimes solve them by providing their adult child with an income from the estate and that income ends when their child dies. If their child's spouse survives their child, not their problem. JMO, I think it might be possible GW4 and JW were going to come into some money, property or both when Billy died and the same may also have been true for the great-grandchildren after their fathers died.
The forged custody docs did two things, at least in AW's mind. They provided custody for JW in the event of HMR's death and they also provided that AW got custody of the children in the event of GW4 or JW's death. Note, they did not provide custody for Billy and AW, just AW. Jake got custody of the child after the murders. Why didn't AW destroy those documents? JMO, I don't think she was sloppy in not destroying those documents, but rather viewed them as "insurance" that she would get custody in the event GW4 and/or JW died. It would work like an annuity, guaranteed income for life, if she could maintain control of both her boys and her grandchildren and groom them to understand it was their job to provide for AW financially.
For JW, I don't think it was about money. I think it was because he lost control of HMR and he wanted to get even with her. JW has had nothing to do but think while he's been in jail and he's been removed from the influence of his mother for a long time. It might be possible he thought AW was on his side as she egged him on, and perhaps he's realized she was only out for herself.
I could be totally off, but this is what makes sense to me. And this is all JMO.