Yes, we could help with this in a premiere support appointment.
using Dynamic drop downs for a parent -> child -> grandchild -> great grandchild structure is not much different then the parent -> child structure.
create additional recordsets for the grandchild and great grandchild lists
add the Create Dynamic Array behavior for the grandchild and great grandchild recordsets
add the Populate list from array behavior to the onchange event of the child list to target the grandchild list.
add the Populate list from array behavior to the onchange event of the grandchild list to target the great grandchild list.