So, as an example, if you have a Boolean field Wear glasses?, and if the user says Yes, then you'd like her to choose the various ways or times they are worn, then define the Checkboxes field Glasses scenarios, enter the possible scenarios, and then Add dependency. In there, identify the Wear glasses? field and the value Yes, then Visible.
Now, if she says No, it shows something else, but if she says Yes, then the Glasses scenarios field checkbox options pop up.
Triggers work an entry at a time, not per each field, so there's no way to script anything to do between fields, only after the checkmark is pressed.