My husband and I have seen this phenomenon as we've observed his ex wife, a true narcissist if we've ever seen one. She has five kids ranging in age from 24-5. The 24 year old got married last year. My husband noticed that his former stepson's wife now lists her hometown as the city where his ex wife now lives, thousands of miles from where the young man and his wife had been living.
I met my husband's former stepson's wife a few years ago. Back then, she seemed only mildly indoctrinated. She let some of her true feelings slip about my husband's ex wife. Sometimes she expressed support for the ex, sounding a bit like she'd been heavily coached; but she also seemed to have some awareness of what was going on. When I heard that she and my husband's former stepson got married, I felt some dread for her. Because I knew that now that she was married, she would be trapped into the mini cult.
As a 24 year old man, my husband's ex stepson and new wife could live anywhere in the country they want to. Yet he's now living close to his mother. I'm sure she pressured him into moving, probably because he's had some trouble finding work... or maybe because she laid a guilt trip on him. The young man has brought his young bride to where the ex lives, away from her comfort zone. I remember so well six years ago, when my husband's ex stepson and his now wife talked about how they avoided his mother's house because "there was no life there." They talked about the ex's current husband, and how he berated the girlfriend's choice in clothes, claiming that she dressed like a slut. It didn't seem like they had great affection for the ex and her new husband. In fact, they seemed a lot more connected to the girlfriend's parents. For that reason, I'm thinking they moved because they felt they had to.
So now the ex stepson's new wife can look forward to her mother-in-law overstepping her boundaries, making snide comments, telling lies about her, trying to drive a wedge between her and her friends and loved ones, and if she ever has a baby, fighting over her child. I suspect the marriage will be fraught with difficulties and will eventually end in a nasty divorce. It may take years, but I think the marriage is doomed... unless my former stepson's wife has either completely surrendered herself or by some miracle, the ex leaves her alone. The young wife did not strike me as the type of person who would do that and I know for a fact that the ex will meddle.
As painful as it's been to be a stepmother to the ghost kids my husband had with his ex wife, I think it would be much worse to be the daughter-in-law to my husband's ex wife. Very soon, that young woman will find out the real truth about my husband's ex wife and will experience her nastiness firsthand-- the lies she tells, the wedges she constantly tries to drive between the people in her life. And if she tries to leave the mini cult, she will be on the outside, perhaps without any offspring she's created.
I know this post sounds dramatic and I wish it were hyperbole. I have been watching for almost ten years and have seen the pattern over generations. Sadly, that's the way it is when you're dealing with a narcissist. You're either with them or against them. Neither position is a comfortable place to be in. You're either strong enough to break free and go your own way with no contact, or you stay in the cult and surrender yourself to the narcissist.