Enhancement: Make any task a subtask via menu

Currently the only way I've found to make Task B a subtask of Task A is to have them both in the same sublist and then drag and drop. This is especially frustrating since one cannot drag and drop in a filtered view (e.g. sorted by date).

As we have a transfer option in the menu, we should also have an option like Subtask... make parent or make child of... That way we can easily relate tasks.