Having some ethnic groups does not create Stake holder of nations. It happens across the world that neighbouring countries have always some ethnic groups common across the border but that does not satisfy the criteria for "Legitimate Stake". In such scenario, Mexican can claim California and Texas.
Hence start looking from stakes perspective in war torned country.
You can say India does not have anything common with Afghanistan but you are forgetting that our borders were with Afghanistan till 1948 (When GB was controlled by Pakistan) and we have always historical relations with them. Many Afghanis were ruler of North India hence and even in current scenario New Delhi is first choice of Indian students. Our relations were put on hold during Russian invasion and during Taliban regime so we are in revival for the same.
Afghanistan does not accept Durand line same as China does not agree on Macmohan and Johnson lines. It is upto you to solve this matter with Afghanistan diplomatically.
Here we are on same points.. Talk something which is your area.. dont poke your noise in matter which is not your area of expertise but these leaders always do..