She looks awfully matronly for 49. Yikes. And she's got an awful lot of white hair for 49 too. Don't you think? I'm not saying it's impossible, but it certainly is uncommon. Furthermore, a 49 year old wouldn't want to go around like that. She would be VERY likely to dye her hair. Why? Because she doesn't want to look like an old lady; that's why.
This next image, according to RO, is from 1958, so two years later.
Well, if anything, she looks younger. And notice that her hair is much darker. You want to say she dyed it? But usually, when a woman is willing to pose for a Mother's Day picture without dying her hair, it usually means that she is done dying it. I remember that my mother used to dye her hair. It was a big ordeal. And I remember that my father would help her. She would lean over the sink, and he would squirt the solution on her hair in back. It was a tri-weekly ritual for years. But once she stopped dying it, she never went back to dying it. And if you look closely at the above picture, you'll see she has quite a bit of grey on the left side of her head, at her temple, which is on our right. So, I am inclined to think that that was the natural color of her hair. Let's look at them together.
They don't look like the same woman to me. The woman on the right is more attractive, frankly. The woman on the left had really puffy cheeks, as in super-puffy, fat cheeks. The woman on the right did not have them. The woman on the right had a larger, wider forehead, and it makes the top of her head look rectangular. The woman on the left has an oval shaped head, and there is nothing rectangular about it.
Let's consider their heights. We know that the Marguerite impostor was very short. But, the woman on the right, in her sitting height, does not appear to be shorter than average. She is not shorter than the other women at that table. They weren't all shrimps, were they?
So, that woman in back is definitely the real Marguerite and not the impostor.
Let's make another comparison to the real Marguerite.
Notice again that we get the sense of a rectangular shaped top of the head on the right and an oval shape on the left. Again, we get the sense of the much puffier cheeks on the left. Although it's hard to see, the teeth are misaligned on the left but not on the right.
Finally, let's compare the image on the left to a known picture of the impostor:
But, there is one more reason why I think the Mother's Day picture has to be the impostor. It's because Robert Oswald showcases it on his website. He does have some images of the real Marguerite, but not close-up like this. I don't think he would showcase such a close-up image of his real mother.
So, I maintain that the 1956 Mother's Day picture is of the impostor, not the real Marguerite, although we have no way to verify the date.