My question is about the issue detailed in this topic: Inheritance shares don't add up to 1. Please read the whole message carefully though, this is not exactly a duplicate. To sum up the point, the Quran contains inheritance laws that specify the shares due to various members of the family of the deceased. Now, there are configurations where the shares add up to more than one.
Now, as has been mentioned in the post I linked, several attempts have been made to fix the issue. The traditional answer would be to use the rules of "Awl" and "Usbah", that is to proportionally change the shares so that all of them add up to 1. Another approach is to keep the shares as stated in the Quran but to distribute the inheritance according to priority rules so that the shares add up to 1 or less. I am dubious however that this last approach works in general. Consider the case of a woman who dies leaving nor ascendants nor descendants, but only her husband and two sisters. Sisters is to be taken with the meaning it has in 4:176, whatever you think the difference is with verse 4:12. Then 4:12 and 4:176 taken together unambiguously state that in that case, the husband should get 1/2 and the sisters 2/3 which adds up to 7/6 > 1. If you don't add man-made laws to the Quran and yet want to keep the shares as stated, priority rules won't work here. Thus, the most rational way would be to reduce the shares proportionnally (that would be 3/7 for the husband 4/7 for the sisters in that specific case). For another example, you may consider the case of a man leaving behind a wife (share: 1/8), a daughter (share: 2/3) and a father and a mother (1/6 each) which adds up to 27/24.
Hence comes the problem. To make sense, it seems that the Quran somewhat needs to be corrected; is other words, the command "give 1/2 to the husband and 2/3 to the sisters", stated as is, sounds absurd and either you conclude that the law of inheritance can't be applied or you're forced to correct it (i.e to literally infringe the original command) to apply the mere "mentality" of it.
Please note that my question really differs from that of the post I mentioned above. I don't expect a comprehensive list of all approaches that have been developed to apply the law of inheritance. I'd really like the discussion to bear on the idea that the Quran's law may need some correcting to be applied.