I think it is a mistake to agree to use the NWT at all. If you must use the NWT then do it only if you can get your hands on an old KIT as well and see where they have made all the changes, use footnotes, Greek, etc...... it is a 'study' after all. She certainly could not object to using their own literature.
I was under the impression that a jw can use other Bibles if absolutely necessary, so do so if possible. Would it be possible to start at the New Testament and read from the beginning to the end without ANY commentary from anybody? not one word, read only. Well, I can tell you it is not possible but be would a way to go. I know, I tried this with my jw and he just could not resist having to say something. That ended that.
jw's have no concept of what a real Bible study is and I agree with you that it is a ridiculous notion that one cannot understand the Bible without the wt. Not only that but one cannot understand the wt's and other rags just by reading them either! one must go to the meetings to truly understand all things jw!
As for her using the 'your not head of the spiritual household' routine! that just pisses me off! anyway, my jw used to try to say he was the head but I simply said that what he was saying was in reference to Christians and he was not one so it didn't apply to him. He didn't claim to be one of the anointed so ......... Jesus was not his personal Savior he only could hang onto the coattails of the 144,000 and Jesus was their Savior hence he was not a Christian but watchowerite. He put his salvation in the hands of the wt therefore he was not a Christian so anything he said held no sway in this house. Yeah, kind of made for ww3 but my kids were safe and are now Christians who will never ever become jw's.
If you are going to err, then err on the side of protecting your kids from this cult that at times physically, emotionally and spiritually abuses it's members.
wishing you all the best,
carla