You Brits always confuse me when you say South Asian, as Asian seems to often be shorthand for Indian/Pakistani/Bangladeshi in the UK, so what is South Asia because I only remember seeing Japanese/Chinese/S. Koreans at MHL sample sale and South Asia means India/Pakistan/etc. in the rest of the world.
I need to have a closer look at the London sample sales as the trains to London are going more often now. How far in advance do they announce it?
Shangpie, yes, that's SSense for you, I think Canadian winters make them extra grumpy over there or something. They also always pick the skinniest models so I assume they're freezing in summer clothes and potentially hangry. The influencers here are driving me batty though, they're everywhere and it's all about video now, they take up so much space as a result, shops, museums, anything is just a prop and a backdrop to them. They're not even looking at the exhibit, just looking for empty spaces they can be filmed in to share a few seconds clip of look I was here. I used to grumble and rant about everyone only viewing museums through the lens of their camera phone, it's so much worse now... Grumble, grumble, I'm on my way to looking like a SSense model.
Sooverthemill, the Schiaparelli exhibit is at the Musee des arts décoratifs (there's also an 80s exhibition with some fashion) but I think this or next week is the last weekend.
I think the YSL museum is reopened but not 100% on that, if you can book ahead and they offer the English tour I'd recommend that.
I'd definitely recommend seeing the Dior gallery, there's a bit of overlap with the exhibition but it's still enjoyable even having seen that. The (expensive) lunch there is also great and a lot of people seem to want to have a glass of champagne there (not sure what that tradition is about). Buy tickets in advance if you can. Mind your feet though, it's very dark in places and the floor levels changes are really badly designed, it's trip hazard central.
The Palais Galleria is sort of the unofficial fashion museum/Chanel gallery. Currently showing a Frida Kahlo fashion exhibit (with the Chanel stuff in the basement, I think), I'm off to see it today. Gorgeous building and grounds but check the dates as they sometimes host runway shows there.
There's a Louis Vuitton popup exhibit across from La Samaritaine in collaboration with a great pastry chef/chocolatier (I'm mostly recommending this one for the pastry chef, it's more of a commercial venture than proper exhibition, really, but still interesting). Bit outside of Paris but not far is the Louis Vuitton foundation, not really programmed for fashion but worth a trip if you enjoy modern art and architecture.
Not fashion related but de Bourse de Commerce is sort of newly opened, currently it's discounted as they're building an exhibition in some of the spaces but it's worth seeing for the building and marriage to new architecture alone. The restaurant/cafe is also great. If you're heading to Venice within the next year get the annual ticket, you'll have access to the two other Pinault collection museums (which are amazing) there too.
Musée du Quai Branly is another museum that I love and is always relatively quiet (see also Institut du Monde Arabe), they have a kimono exhibition going at the moment.
For shopping in the Marais and taking in consideration the brands you'd like to visit I'd go to The French Trotters and AB33 boutique. You might also like Loulou studio which also have a shop in the Marais now. Roseanna in the sale might appeal. If you're in Saint Germain I'd go to the Smallable for women boutique (it's not very big though, wouldn't make the trip for that alone). For food I have many recommendations but it sort of depends on preferences and budget.