Wow. Just wow. I love your posts :)
I've tried that exact sanctifying His Father's name thing with JWs too. Never got any further than you did. But it's one of those...sure, Jesus knew it, but does He call His Father by the proper name, or would He call him Father? If your dad's name is Bob, do you call him Bob or dad? He instructed us to call Him Father. Not a personal name.
The divine name was edited out of the scriptures about 250 years before Jesus' birth. The Jews were very superstitious and didn't believe it should ever be uttered out loud. They used Elohim or Adonai instead. So it was replaced with LORD long before Jesus. Even if He did say the actual name, it isn't Jehovah. Jehovah is an anglicized version of YHWH invented by a Catholic monk in the 13th century...Raymundus Martini. Jehovah is a false name. Yahweh would be closer. No one on earth knows the correct pronunciation, but scholars agree that Jehovah makes no sense in Hebrew and is a very bad translation. Earlier, some JWs I was talking to were saying Jehovah is English so it's easier and if someone named Juan came to the US and people couldn't pronounce it, they'd probably call him John. But this argument is silly...cause how hard is it to say Yahweh over Jehovah?
If she really wants to go over the Bible teach book with you, I say go for it. But prepare first. There's a man that wrote a book dissecting it - Wilbur Lingle. He takes it section by section to prove how wrong it is and gives lots of leading questions, one after the other, to reach the ultimate question for a particular point. By the time you reach that one, the JW is totally stuck and it should really make them think about what that book says. You can read it here: http://thesnarkyapologist.blogspot.com/ (Response to What Does the Bible Really Teach - how to respond to this publication).
Looking forward to your next post :)
EDIT: Island Man has good points. There are scriptures that are clearly speaking about Jesus but it says Jehovah. They've added it many, many more times than what is quoted from the OT.