dude. People in those regions have repeatedly and peacefully participated in Indian electoral processes since Indian independence. You can conduct any survey you want, not even 10% of that region wants to independence or merger with China.Okya, let South Tibet hold a referendum and let the South Tibetans decide India&independent&China by themselves. Let the P5 of UN supervise the voting. We can recognize the result of the vote.
Referendum is a strong word not to be taken lightly. Why should India allow referendum on Indian soil just because China claims it?
Will China allow referendum in Tibet, Xinjiang, Taiwan etc ?
You can clearly see the people's will in Arunachal and Ladakh and you do not need a referendum to know where people want to be.