This kind of article rubs me the wrong way. Starting way back with Diana vs Sarah, Kate vs Meghan and now a rewarming of Mary vs Marie, the press figured out that cat fights between women sold papers.
Most of these sister-in-law feuds are cooked up to sell papers and generate clicks, especially during the quiet holiday season when the press needs to generate traffic to the site. I don't see anything new here, just a sad attempt to sell papers. If there is a personality clash, my guess is it's between the brothers.
Mary and Marie don't seem to be close, but I don't think they are at daggers drawn either. I don't they they interact enough to be enemies. There might be issues within the DRF, but I don't think it's fair to lay all the blame at Mary's door either.
Gosh, I don't mean to be such a Mary sugar, it's more that I wish the public wouldn't fall for the feuding sister-in-laws storyline each time the media casts about for something juicy to draw in readers.
I see Mary as a very insecure person, who would be afraid of anyone, who might be a threat to her.
Mares may live in her own world, but I don't think she isn't intelligent enough to figure out that she isn't really liked in the family. That Marie is originally French (as was Marge's beloved Henri) is of course another slap in the face for her (not to say that Marie is openly prefered by Daisy).
As for Marie I believe that she doesn't care at all for Mary, but in fairness to Mary I also think that Marie had/has it much easier in the family. Of course Mary's character doesn't make her very likeable as a whole, but both sides (family vs. Mares) also don't really seem to try to overcome their differences.