Hi Chickie!
My guess (and it's just a guess) is that they do this to everyone, and not just you. I'm wondering if DS is not being treated the same way by her in his own home. Someone that is that scared to even talk (and I'm just speaking from my own experience) can have alot of things going on at home, and it's hard to tell what goes on behind closed doors. There are just so many possibilities. When people feel superior to other people, I believe they are like that with family also, and I can remember a man I dated for a few months about a year and a half ago. He was the head of a division of homeland security here and had lots of money. Picked me up in a Porsche, took me to plays, dinner theatres, bought me a complete wardrobe for his house. He wanted me to move in so he kept asking sizes and before I knew it his house included every I needed without packing anything. Then he started pressuring me to move in. He wouldn't take no for an answer and I finally had to break things off. But he was wealthy and my little brothers wife told me I should hang onto him because of his money. The thing was, he was "superior." He talked about his neighbors, his son's wives, everyone. He was forceful about me moving in with him, and when I would explain to him that I couldn't move out and live with him, he came up with excuses for everything I told him. He didn't want me to have anything to do with my parents, my kids and I could even see that he didn't like my dog. He lived in a mansion with a huge pool in the back yard, exercise room, jacuzzi, - I'm sure you can see where I'm headed. He was trying to buy me away from my family, but I could see how superior he felt toward my family. When I finally called things off, he asked that I give him back gifts he had brought me (which I was only too glad to return by then). I believe he thought that I would break down at the thought of returning them, but I didn't (diamond necklaces that he had insured, a gold watch,...) He tried to give me 20,000 to pay off my car, but I refused to take it - thank God. Boy would that have been hard to pay back.
Anyway, this is what I'm try to say may be the problem. Some people who have this superior view of themselves believe they should have everything their way and don't really put a value on people. Money is it, and since they already have this money, they will use it to control other people around them with it. This man was an expert, and I'm assuming that since your DIL's family has money, this may be their lifestyle. The friends they have are controlled. I'm not saying this is right. Just that this is my own experience with this man here. If I had gotten involved with him to the point of moving in, I believe I would be in a marriage now that would have me fearful too. Some people just use things, money and even children like that to control others. Your son may be experiencing some sort of blackmail, but I don't know. He may never tell you.
Chickie, this is just so hard to guess at. I hope you get other replies, because I'm not sure my experiences are good enough to make guesses with here.
What were you thinking the problem was? Can you write it down so we can all brainstorm?
Also I think Luise would be better at this one. My opinion is tainted.