Salaam,

If the Quran is to be the only source of religion, then surely it should be clear in all matters? But what we find in 4176 is that there is some inherhitance left over, and the Quran doesn't specify what to do with this inheritance

They request from you a ruling. Say, "Allah gives you a ruling concerning one having neither descendants nor ascendants ." If a man dies, leaving no child but a sister, she will have half (1) of what he left. And he inherits from her if she has no child. But if there are two sisters, they will have two-thirds (2) of what he left. If there are both brothers and sisters, the male will have the share of two females. Allah makes clear to you , lest you go astray. And Allah is Knowing of all things}

Now as per my # references (1) and (2), what is to be done with the 1/2 after the sister gets her share and the 1/3 after the 2 sisters get their share? Now remember, the answer, according to a Quran only intepratation, must come from the Quran alone and not any other book, not even other Ayat that do not relate to this particular ruling nor your 'understanding' or anyone elses. Is this possible?