Does the Quran inheritance law also apply for non-Muslim descendants and siblings?
There are two aspects of this question:
1- Do non-Muslims fall heir to Muslims?
In Qur’an, there is no verse that forbids non-Muslims from falling heir to Muslims. Right on the contrary, there is no differentiation among heirs from the points of ethical or religious situations of heirs, in Qur’an. The verse An-Nisa 4:92, also mentioning that the diyat of a deceased Muslim should be given to his dhimmi non-Muslim family, is supporting evidence besides the verses about inheritance. Although there seems to be a ban about this in some hadiths, upon research it becomes evident that this ban is limited to the times of war between Muslims and non-Muslims.
2- Are non-Muslims subject to Islamic laws?
If non-Muslims are under their own land/government of jurisdiction, they apply their own laws and Islamic laws cannot be applied. Related verse is:
“If they come to you, judge between them, or turn away from them. If you turn away from them, they will not harm you in the least. But if you judge, judge between them equitably. God loves the equitable.” (Al-Maidah/The Feast; 5:42)
A Muslim tries to get his right either according to Islamic or to effective laws. Apart from this, if other non-Muslim heirs do not give him his due, he cannot do anything further.