As far as my research have found there is currently no way to make a Parent and child task in the Eden editor without using script commands. This is something thas functions such as BIS_fnc_createTask does support so it should be supported by the modules as well.
I suggest either
1. Modifying the existing Create Task module to allow entry of a parent. Maybe syncing or grouping the modules could be used to allow easy control.
or
2. Adding a new kind of Create Child Task module that must be synced or grouped to a Create Task module to work.