Why are you dragging Pakistan into this? No one in the Pakistani-administered areas wants to join India, and virtually no one in the Indian-administered areas wants to join Pakistan.
The Kashmir Valley is apparently the only area in the entire former princely state where most of the population favors some sort of change in sovereignty, and it has repeatedly been shown that the overwhelming majority there only want independence.
Again, tying the fate of the whole colonial state together is only going to breed further instability in the region.