My mum, in her mid sixties, is kind of a nightmare when it comes to stirring/enabling among my siblings and dad (parents been separated for years). It seems like she tries to create drama/cause problems/look for reasons to get upset (or, alternatively, play "rescuer"), but it's most obvious, to me, with how she acts towards my sister.
My sister, early 30s, is anorexic. She has been anorexic for nearly 20 years. She's been hospitalised a few times, in and out of treatment, some suicide attempts, self harm etc. bla bla bla. She's had some periods of relative wellness and others of very acutely medically serious illness, but for the last five years or so she's been stable BUT still extremely disordered and extremely underweight. Her weight is around 38-40kg and she's average height . She is very good at pretending to be happy and "normal" in front of family and we haven't seen much of her since covid anyway but it's clear from her weight and various things going on in her life that she's not actually fine.
Anyway, my mum has a habit of approaching DSis and asking her if she wants XYZ item of clothing my mum has ordered online and doesn't like or doesn't quite fit into. Mum's a size 12 with a typical middle aged woman who has had several children shape. For the avoidance of doubt, DSis is smaller than the smallest sizes you can get on ASOS or anywhere, has no boobs, no butt, no hips, no belly. It's not like she asks me if I want them, even though I'm a size 8-10 and have a more similar style to my mum. TO BE CLEAR: I'm not aggrieved that my mum never offers me her unwanted items! I'm just perplexed as to why she KEEPS approaching my sister in this way as if to suggest they're almost the same size.
Whenever this happens, DSis will send me eye rolly screenshots of their text conversations, but she has also told me that it seems like mum is trying to upset her by implying she's bigger than she is -- and even though we can joke about it together ("typical mum" "got another bingo" type thing), I know that this stuff DOES upset her.
What the hell is mum thinking?
Other times she's given DSis birthday presents of diet books or other like, diet/food paraphernalia -- think food scales or spiraliser rather than a kitchenaid or a fondue set. She will also ALWAYS comment on what DSis is eating, if she is eating.
Obviously, after decades of this I don't expect she is going to change her ways. And DSis is "used to it" to some extent, and has her coping mechanisms -- to an extent. But it pisses ME off! And I know it does affect Sis too.
All i'm wondering is: why is she like this? What on earth is she thinking?
I'm not very good at imagining other people's motives, admittedly, but I'm totally clueless about what she's trying to achieve. Is there a charitable interpretation for her doing things seemingly deliberately to trigger my sister's eating disorder?