The problem you have Sir is that the JWs will totally cut you and your wife (and child) off from her family. This you are probably finding out. The doctrines of the JWs are complex and ever changing and depending on your particular situation totally impossible to predict as to outcome. Some of the advice you are getting here is what could be defined as hostile to the family, the JWs even more so.
If you are still looking for free advice, mine would be for you and your wife to have a free and frank discussion on where you want to go as a couple. If you can create a united front and craft a rock solid relationship then no matter who gets their feeling hurt because you took a path they didn’t agree with your marrage and family will stay strong. My inlaws basically wrote my wife and I off due to religious beliefs and it was hard to cope with but we managed because we were in agreement on religion and had a relationship stronger than the desires of our family to share their religion.
I wish you well.
Jon