I agree, it is all about control and doesn't make any sense. I see so many similarities in your story. My husband got DF'd for dating me and having a child. I was the unbeliever. We did not marry nor was he was not reinstated until over a year after our child was born. During that year his parents delt mostly with me on a daily basis because they babysat our baby and my other child from a previous relationship. We got along well. His mother would even come over to our place and visit me and the children (their DF'D son, my boyfriend at the time, would stay in the bedroom). It wasn't until I was close to getting baptized that it dawn on me that her visits were also a source to get field service time as she was a regular pioneer. That may not heve been her only intention and probably an excuse to give her husband for visiting and/or it could have been a way for her to check up a little on her son, who knows?-It's warped thinking but allowed her to justify feeding into her human side. My point is, if its enough wiggle room for a JW to use and not bring reproach on Jehovah they may use it. Most parents want their children happy and want to support.
As far as them attending your wedding, I can understand how hard that is. That's another crazy thing, my inlaws attended their bible study's ceremony at the justice of the peace but couldn't attend ours at the justice of the peace, of course he was disfellowshipped but even if he wasn't they couldn't because I was an unbeliever.
This brings me to another point, your other difficult situation, I assume your son is from a believer. That's sort of where I am with my children, trying figure out how to keep them from getting baptized. My husband currently is not aware of my doubts, and there is some pressure for them to get baptized. I'm stilling researching and trying to figure out my own feelings before I can address this but It will not be long before I need to take a stand for their sake. I imagine you will eventually have to do the same. Aside from all the other issues bought on growing up as a witness, If he gets baptized and you are no longer in you will run into the same issues you are going through now if he ever decides to get married, will you be able to attend the wedding? I can understand to a degree what you are going through.