Pasture rights and borders

This article from ANI raises some very serious questions which are generally ignored by political commentators.
How to demarcate a border which has only been delineated (like the McMahon Line which was drawn on a small map after a vague survey)?
In this particular case, the main principle used by Sir Henry McMahon and his Tibetan counterpart (Lochen Shatra) to draw the border between India and Tibet on the two-page map was the watershed principle.
Unfortunately the line of the highest  ridges is not always a straight line. 
What to do in this case?
One way to demarcate the border is to use rivers, lakes, roads and other natural features or more interestingly pasture rights.
It does not always work, as for example, some pasture may have been leased by some villagers one side of the ridge to villagers on the other side. What to do in such cases?
Further, this lease may also be a time-bound (1 year/5 years/100 years, etc.) one. In any case, lease does not mean ownership.  
About ownership, what is a proof of ownership? Possession only? It can be customary ownership dating from centuries which often involves disputes between villages.

Without going into details, it is a tricky issue and it is one the reasons why the McMahon Line has never been demarcated on the ground.
At the end of the process, when both sides have agreed to demarcate the border on the ground, abornement (or erection of pillars/fence) has to be done.
This may take several decades in the case of McMahon Line. 
For Bhutan, it may be easier.
In The McMahon Line Saga, I mention the agreement on delineation of the Indo-Bhutan border in this sector:

During the 1938 Lightfoot’s trip [Capt Lightfoot was the Political Officer in Balipara; he was responsible for the Frontier's Tracks], the alignment of the Tawang-Bhutan boundary was again discussed with the Bhutanese authorities.
Lightfoot’s recommendations were more favourable to Bhutan than the 1936 line. The 1938 line ran along the Warong Chu near Bleteng, then along the Tawang Chu and from there along the Ngangrang Chu to the Nyingsang La ridge. This was officially communicated to the Bhutan Government through Political Officer in Sikkim in November 1938 and accepted in July 1940. Till date, it has remained the de facto boundary.

Once again, delineation does not mean demarcation.

Arunachal GBs oppose Army’s map putting 22 grazing grounds outside of India
ANI
News Desk
October 29, 2012
Tawang, Oct 29 (ANI): Claiming that the Indian Army has in its border demarcation map put 22 grazing grounds outside of Indian territory, the All Arunachal Pradesh Goan Burah Welfare Association (AAPGBWA) today said villagers would not allow their land to be given away to Bhutan.
AAPGBWA president Nabam Epo informed that a team visited the district and identified the grazing grounds of Lumpo Muchut village as Manamla Pass, Ranti Kirme, Breuser, Phojurmo, Serchuangla Pass, Serchung, Sargosla Pass, Sargosche, Berfo, Sargoti, Brimala Pass, Chhegorla Pass, Barila Pass, Talemjurche, Morokser Law Pass, Morokser, Berfo, Talemjurtee, Gila Pass, Laqyap, Dumsumteng and Gamola Lachangtso.
The AAPGBWA also called for lifetime tenure for GBs, as long as they did not breach conditions of appointment, and urged the Arunachal Pradesh Government to provide all amenities/facilities due to GBs under the relevant Act.
Gaon Burah as an institution assumes importance in the villages of Arunachal Pradesh in the absence of separate judiciary in the state.
The senior most Gaon Burah is appointed as the head Gaon Burah and its members are the elders of the village.
The council meets whenever necessary to settle the disputes. Oaths and ordeals are also used to arrive at the final decision.
The members of the council are held in high esteem and the council performs judicial, developmental and administrative functions as well. (ANI)