Embedded data in unanswered questions?

Greetings gang, so here's the deal, in my registration survey I take the entered info and inject it into my XM Directory as embedded data fields (via Contact List trigger). Nothing new there but my problem is this: when a person fills out the survey it records their information including address. So there is a field for "address (line 2)" where people usually put things like "apt 1" and such. This all works fine and without issue. The information shows up in their Directory entry in an embedded data field called "Address2". The problem is that if they take the survey again later (say after they move) and leave that text box empty (maybe they've moved into a house with no "address line 2" that empty entry is *not* injected into the Directory to replace the previously entered "apt 1".

So I really have two questions:
1. How do I make sure that if a field is left blank, that "blank" (empty) field is put into the embedded data field for that person?
2. Say I have 20 questions in my registration survey and 5 of them have display logic attached to them so they are only shown if the person selects "yes" for a previous question's answer. The first time through the registration survey they say "yes" to this initial question and then see the 5 other questions and fill those out (which have contact list triggers on them so the answers to those 5 become stored as embedded data in the Directory). Then, a year later they take the survey again to update their info and they now select "no" for that initial question. So now they aren't going to see those 5 display logic questions--how do I blank out (empty) those 5 questions when the Contact List trigger fires?

For #1 I tried putting a single space as a "default choice" did not work (it didn't change the embedded data field injected into the Directory from what it had been the previous time_ and I also tried the following Javascript: Qualtrics.SurveyEngine.setEmbeddedData("Address2", jQuery("<span>${q://QID90/ChoiceTextEntryValue}</span>").text());