This was my life, the poorer, disabled daughter who got closed out. My list includes my mother and sister visiting each other several times a year, driving by my apartment within a mile and never stopping by or visiting me or including me, secret family/ and other parties my mother would hold and not tell me about, shopping trips, extended vacations to Florida where even another disabled member got a trip all paid for to go, being disinvited from weddings and more. Often I was told, "You don't have the money", or "You can't do all the walking" the few times I found out. Most of the time, the response was "We are busy!". My mother would visit every third cousin in a 1300 mile radius but would never see me. My sister once told me, "I don't travel" when I asked her to stop by on the way to see someone else, and in the next breathe mentioned a Florida vacation. In my family the same "class dynamics" apply, the poorer are left out and ostracized, sometimes dealt with so they can come pay homage but basically left out of the lives of many others.
It saddens me to hear of her sister crying. If these people do not repent, there isn't a hot enough place in hell for these types but these were the kind of people I was dealing with too. All they care about is status, and image. The advice columnist is right she did not learn much in church. All of mine too attend church playing pious.
One thing as you know I confronted both for many years, but all I got told was that I was a liar and gaslighted to death. The path of healing for the sister being written about by this would be narcissist is to be done with all of them and find "sisters" among friends. That is what I did. She can then be free of the pain of her broken-heartedness. It will take time but it can be done.