But if it was an accident leading to a cover up/false kidnapping report, I honestly believe that no one in the family would just dump the baby in the river or the woods. If this is what happened, LE needs to find a more proper grave...so to speak. The family members would probably have taken her to some place peaceful and secure where they could give her a more proper burial and service. These people don't seem like the type to dump Lisa in a dumpster, river or woods.
Land familiar or special to either DB or JI is where searches would seem the most logical. If DB enlisted help from another family member then LE should start interviewing the family, friends and neighbors over in Independence, MO. One brother and one grandparent are listed as living there as well as an aunt and at least one cousin.
It is possible that Lisa was taken somewhere temporarily and then a family member went to retrieve her for a more fitting burial.
There is still the possibility that Lisa was taken/abducted or that she was given to someone. The latter being the most unlikely as almost too much time has gone by for this to be a successful fake abduction.