An error occurred while saving the commentThomas Henkelmann commented
I would not try to duplicate functionality that exists in Project Online or Project Professional i.e. build a schedule with predecessors and successors. A simple "this task belongs to..." with a list or maybe even only one other tasks would already help a lot. And it could be integrated into the promotion of checklist items: when you promote a checklist item to a new task it could automatically inherit "I belong to my former task".