The whole nuke doctrine has many scenerios which include death of political leadership and how the nuke command will work in such a situation. who will control the nuke trigeer and who will assume command is all very well laid down. I do not wish to share much on this open forum but indian political leadership will not be in Delhi but in some very very safe place with complete control of all assets on ground and in air and at sea. In any case, in case of nuke war with Pak, I do not envisage the battle to last more than 24 hrs. Pakistan will be decimated within that time.
As will India. Pakistan has 90-110 nuclear warheads, and is adding a dozen or so each year. Pakistan's nuclear technology and delivery systems are on par with India's as well.
What nobody here seems to be understanding is that since India is engaged in this nuclear arms race with Pakistan, and India also tends to make noises against China from time to time, China could hint to India that the next time India complains or intrudes in the SCS, China will let Pakistan 'steal' road-mobile MIRV-capable IRBM technology, advanced penetration aids designed to defeat US ABM systems, and miniaturized thermonuclear warheads based off research acquired from the US Los Alamos laboratory (especially warheads modeled off the US W88, which is now China's stock-standard warhead model).
This would turn Pakistan's nuclear arsenal from a collection of inertially-guided 20-25kt warheads that take 30 minutes to hit, into a bunch of GPS/precision-guided 400-550kt warheads with multiple decoys per warhead that take less than 15 minutes to hit their targets, designed to defeat not just India's attempts at ABM but the real big boys of ABM, the US and Russia.
It's a huge point of strategic leverage against India, because India and Pakistan are both decades away from such technologies, and there's nothing India can do to stop it.
Given this fact, were I a rational Indian planner, I would be pursuing a disarmament treaty with Pakistan post-haste to rectify this vulnerability, but it seems that no Indian politician has the political courage to pursue such a course of action, and the BJP seems hell-bent on pursuing an alternate course of confrontation and blowing $$$ on doubling the manpower of the land army...