Since you didn't post #39 here: It's nice of Miriam to try to help her daughter get more business, sure, but I think she just likes messing with Victor now too. And much as I love the witches, Victor is actually a bit right about them. At least Wilfreda has learned how to deal with him effectively now.
Then it's really nice of Wilfreda to still offer Victor some of her lemonade so that he can try for himself. Maybe his luck would turn around only in that he'd make a new friend instead of always being irritated with her. Of course, with him being skeptical and Betty having reservations I wonder if they'll get together and devise some kind of double-blind, controlled experiment to test out Wilfreda's claims before the FDA is forced to create a whole new label for magical foodstuffs. (I'd write a fanfic about Betty and Victor doing that, but there's too much risk of it straying further from the source material than you'd like. )
Second, Miriam likes messing with everybody, except we just saw her interact with Victor (also, she really likes to protect her daughter) and the other kids haven't yet given her any reason to bother. Key word is "yet". Milagros is most likely to be next.
Third, you better believe the experiments are coming, but not in the way you think, and they might introduce a new character! Stay tuned for THAT!