Greta certainly does not want to stir the pot. On the contrary. Hence the questions about how to make things as smooth as possible .
Not stirring the pot is incredibly easy. She just has to nod if she meets Nadine, smile and say something nice like "A lovely wedding."
By bringing this up with other people, I sense Greta is looking for validation on NOT making it "smooth as possible." Either that or she's unable to adjust to the concept that the Mother of the Groom isn't the wife of the Father of the Groom, and feels that talking to her at all would erase Jocelyn. For example, she doesn't *have* to seek out Nadine, but if she meets her, she acts the way one would around a member of the groom's family she hasn't seen in a long time, and has no particularly strong feelings about.
This isn't Highlander, where There Can Only Be One.
I had a similar sense to the bolded. whiterose, you know Greta, and we don't, and I believe you that she says, and believes, that she doesn't want to stir the pot.
But there seems to be no reason to expect that there will be any drama, or anything close to it, unless she
makes it. It simply isn't a big deal who says hi to whom first, or if she makes a point of going to say hi to Nadine or just waits until she bumps into her, so the very making of a plan about it
is stirring the pot or anyway cranking up the drama.
At many, maybe even most, weddings, there are ex-spouses, and people like Greta and Lars who once were related to one of them but aren't anymore. And tons of other complicated relationships much more stressful than this one. It's not a problem unless someone makes it a problem.
And here, it seems like the stakes could hardly be lower. There is no mention of anything truly heinous that Nadine has done to Greta or that she is bothering anyone now. Greta hasn't even seen Nadine in decades and will probably only see her a few more times ever -- weddings, funerals. Whereas Jocelyn, Levi, and Adrian are in a much closer relationship -- and they have evidently made their peace, at least enough for Adrian to be in touch and for everyone to be able to get along.
So why does Greta think that her role in this is anything other than insignificant, or that anyone would care or even notice whether she makes a point of approaching Nadine or not? It is hard to escape the feeling that at some level she is hoping for a little drama or at least self-importance.
It's so easy: "Hi, Nadine. Congratulations! It's been ages; how have you been? ... Oh, that's nice. What a pretty dress. Did you get any of that great bean dip? Have a good time!"
What alternatives to simply being pleasant and polite to Nadine did Greta say she was considering? Cold silence? Confronting her with 20-year-old grievances? Punch in the snoot?
Adrian's wedding is a time to contribute to his joy and be a gracious guest, not to make trouble or call attention to oneself. There is only one choice here that will serve that.