I found an interesting fact about why there was a complete lack of planning on managing the vast exodus of refugees that started after the announcement of Partition.

Excerpt below from a research article by Omar Khalidi, Aga Khan Program on Islamic Architecture, Massachusetts Institute of Technology, Cambridge, Massachusetts, U.S.A.

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Although some observers feared that partition would lead to violence and forced migrations, they apparently did not anticipate mass migrations. At a press conference in New Delhi on 12 October, 1947, Prime Minister Jawaharlal Nehru admitted that there was "no policy with regard to exchange of population [between the two countries] and that there was no talk of it before August 15... None of us envisaged a major transfer of population at any time".

It was assumed that the future country of Pakistan would contain the majority of Muslim population, but it was still expected to have measurable Hindu and Sikh minorities in it. Indeed it was rationalized by some that the Hindu minority in Pakistan would be "hostages" for the good behaviour of India towards its remaining Muslim minority. Because leaders of both future countries of India and Pakistan took pains to emphasize that they would protect these minorities, large scale migrations would seem unnecessary.