I'm not aware of the inspiration behind this story but I guess it must be biographical: yet this is not overly important for the viewer, except for the intimate care we can feel the author put in the production. I loved it.
An apparently minor work which reminded me of 2 other recent films: "August: Osage County" (AOC) and "Roma" which in some sense represent extremes of family life portraits styles.
On one side "AOC" scenes and dialogues are so unrealistically poignant that even people with an IQ of 200 would never talk like that (and that fast).
I hardly doubt anything except some irrelevant details is historically accurate there: everything feels designed for some purpose. Which is not necessarily bad, just like authenticity isn't de jure good.
"Roma" is instead authentically documentaristic in its depiction of events. Yet such elegant realism actually left me detached: I was pleased but I was rarely touched as if repelled by the same barriers we use to protect ourselves from the world.
"Le sorelle Macaluso" lies elsewhere: it doesn't offer neither incisive dialogue nor objectivity. Is that a stylistic decision, just accidental or the magic of a masterpiece? I don't care as long as I care so hard for what I see.
On the negative notes: in "Le sorelle Macaluso" unfortunately the characters are somewhat painted with a brush heavier than it could/should have been (and I mostly blame the writers, not the actresses which are on average very good). Too many things aren't ligthtly touched on and left for the viewer intelligence to understand.
Photography is also weak - especially compared with the previously mentioned movies - while music - although unoriginal - features some great choices.
All in all 4-5 scenes alone deserve my praises and justify the view.
In particular I found the last 5 mins scene extremely moving, delicate, tragic, poetic and universal: unforgettable. I'm not aware if it's an "original" or the author "lent" it somewhere else: anyway you shouldn't miss it.